diff --git a/crates/voicevox_core/src/engine/full_context_label.rs b/crates/voicevox_core/src/engine/full_context_label.rs
index 9c0e28a25..b8e3cce2d 100644
--- a/crates/voicevox_core/src/engine/full_context_label.rs
+++ b/crates/voicevox_core/src/engine/full_context_label.rs
@@ -4,7 +4,7 @@ use super::*;
 use once_cell::sync::Lazy;
 use regex::Regex;
 
-#[derive(thiserror::Error, Debug, PartialEq)]
+#[derive(thiserror::Error, Debug)]
 pub enum FullContextLabelError {
     #[error("label parse error label:{label}")]
     LabelParse { label: String },
diff --git a/crates/voicevox_core/src/engine/open_jtalk.rs b/crates/voicevox_core/src/engine/open_jtalk.rs
index c2d28efbe..60c3acbf1 100644
--- a/crates/voicevox_core/src/engine/open_jtalk.rs
+++ b/crates/voicevox_core/src/engine/open_jtalk.rs
@@ -14,36 +14,6 @@ pub enum OpenJtalkError {
     },
 }
 
-impl PartialEq for OpenJtalkError {
-    fn eq(&self, other: &Self) -> bool {
-        return match (self, other) {
-            (
-                Self::Load {
-                    mecab_dict_dir: mecab_dict_dir1,
-                },
-                Self::Load {
-                    mecab_dict_dir: mecab_dict_dir2,
-                },
-            ) => mecab_dict_dir1 == mecab_dict_dir2,
-            (
-                Self::ExtractFullContext {
-                    text: text1,
-                    source: source1,
-                },
-                Self::ExtractFullContext {
-                    text: text2,
-                    source: source2,
-                },
-            ) => (text1, by_display(source1)) == (text2, by_display(source2)),
-            _ => false,
-        };
-
-        fn by_display(source: &Option<anyhow::Error>) -> impl PartialEq {
-            source.as_ref().map(|e| e.to_string())
-        }
-    }
-}
-
 pub type Result<T> = std::result::Result<T, OpenJtalkError>;
 
 pub struct OpenJtalk {
@@ -131,10 +101,9 @@ impl OpenJtalk {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use pretty_assertions::assert_eq;
     use test_util::OPEN_JTALK_DIC_DIR;
 
-    use crate::*;
+    use crate::{macros::tests::assert_debug_fmt_eq, *};
 
     fn testdata_hello_hiho() -> Vec<String> {
         // こんにちは、ヒホです。の期待値
@@ -230,7 +199,7 @@ mod tests {
         let mut open_jtalk = OpenJtalk::initialize();
         open_jtalk.load(OPEN_JTALK_DIC_DIR).unwrap();
         let result = open_jtalk.extract_fullcontext(text);
-        assert_eq!(expected, result);
+        assert_debug_fmt_eq!(expected, result);
     }
 
     #[rstest]
@@ -243,7 +212,7 @@ mod tests {
         open_jtalk.load(OPEN_JTALK_DIC_DIR).unwrap();
         for _ in 0..10 {
             let result = open_jtalk.extract_fullcontext(text);
-            assert_eq!(expected, result);
+            assert_debug_fmt_eq!(expected, result);
         }
     }
 }
diff --git a/crates/voicevox_core/src/engine/synthesis_engine.rs b/crates/voicevox_core/src/engine/synthesis_engine.rs
index f7b63c22e..b16271a50 100644
--- a/crates/voicevox_core/src/engine/synthesis_engine.rs
+++ b/crates/voicevox_core/src/engine/synthesis_engine.rs
@@ -647,7 +647,7 @@ mod tests {
     use pretty_assertions::assert_eq;
     use test_util::OPEN_JTALK_DIC_DIR;
 
-    use crate::*;
+    use crate::{macros::tests::assert_debug_fmt_eq, *};
 
     #[rstest]
     fn load_openjtalk_dict_works() {
@@ -655,10 +655,10 @@ mod tests {
         let mut synthesis_engine = SynthesisEngine::new(core, OpenJtalk::initialize());
 
         let result = synthesis_engine.load_openjtalk_dict(OPEN_JTALK_DIC_DIR);
-        assert_eq!(result, Ok(()));
+        assert_debug_fmt_eq!(result, Ok(()));
 
         let result = synthesis_engine.load_openjtalk_dict("");
-        assert_eq!(result, Err(Error::NotLoadedOpenjtalkDict));
+        assert_debug_fmt_eq!(result, Err(Error::NotLoadedOpenjtalkDict));
     }
 
     #[rstest]
diff --git a/crates/voicevox_core/src/error.rs b/crates/voicevox_core/src/error.rs
index 3835b678d..f4e3f882b 100644
--- a/crates/voicevox_core/src/error.rs
+++ b/crates/voicevox_core/src/error.rs
@@ -68,50 +68,6 @@ pub enum Error {
     ParseKana(#[from] KanaParseError),
 }
 
-impl PartialEq for Error {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Self::NotLoadedOpenjtalkDict, Self::NotLoadedOpenjtalkDict)
-            | (Self::GpuSupport, Self::GpuSupport)
-            | (Self::UninitializedStatus, Self::UninitializedStatus)
-            | (Self::InferenceFailed, Self::InferenceFailed) => true,
-            (
-                Self::LoadModel {
-                    path: path1,
-                    source: source1,
-                },
-                Self::LoadModel {
-                    path: path2,
-                    source: source2,
-                },
-            ) => (path1, source1.to_string()) == (path2, source2.to_string()),
-            (Self::LoadMetas(e1), Self::LoadMetas(e2))
-            | (Self::GetSupportedDevices(e1), Self::GetSupportedDevices(e2)) => {
-                e1.to_string() == e2.to_string()
-            }
-            (
-                Self::InvalidSpeakerId {
-                    speaker_id: speaker_id1,
-                },
-                Self::InvalidSpeakerId {
-                    speaker_id: speaker_id2,
-                },
-            ) => speaker_id1 == speaker_id2,
-            (
-                Self::InvalidModelIndex {
-                    model_index: model_index1,
-                },
-                Self::InvalidModelIndex {
-                    model_index: model_index2,
-                },
-            ) => model_index1 == model_index2,
-            (Self::ExtractFullContextLabel(e1), Self::ExtractFullContextLabel(e2)) => e1 == e2,
-            (Self::ParseKana(e1), Self::ParseKana(e2)) => e1 == e2,
-            _ => false,
-        }
-    }
-}
-
 fn base_error_message(result_code: VoicevoxResultCode) -> &'static str {
     let c_message: &'static str = crate::error_result_to_message(result_code);
     &c_message[..(c_message.len() - 1)]
diff --git a/crates/voicevox_core/src/lib.rs b/crates/voicevox_core/src/lib.rs
index 90a2bc93a..88cb39be7 100644
--- a/crates/voicevox_core/src/lib.rs
+++ b/crates/voicevox_core/src/lib.rs
@@ -3,6 +3,7 @@
 /// cbindgen:ignore
 mod engine;
 mod error;
+mod macros;
 mod numerics;
 mod publish;
 mod result;
diff --git a/crates/voicevox_core/src/macros.rs b/crates/voicevox_core/src/macros.rs
new file mode 100644
index 000000000..db0a4de83
--- /dev/null
+++ b/crates/voicevox_core/src/macros.rs
@@ -0,0 +1,45 @@
+#[cfg(test)]
+pub(crate) mod tests {
+    use std::fmt::{self, Debug};
+
+    use pretty_assertions::StrComparison;
+
+    /// 2つの`"{:#?}"`が等しいかを、pretty\_assertions風にassertする。
+    ///
+    /// `io::Error`や`anyhow::Error`を抱えていて`PartialEq`実装が難しい型に使う。
+    ///
+    /// # Panics
+    ///
+    /// 2つの`"{:#?}"`が等しくないとき、assertの失敗としてパニックする。
+    macro_rules! assert_debug_fmt_eq {
+        ($left:expr, $right:expr $(,)?) => {{
+            crate::macros::tests::__assert_debug_fmt(&$left, &$right, None)
+        }};
+        ($left:expr, $right:expr, $($arg:tt)*) => {{
+            crate::macros::tests::__assert_debug_fmt(&$left, &$right, Some(format_args!($($arg)*)))
+        }};
+    }
+    pub(crate) use assert_debug_fmt_eq;
+
+    #[track_caller]
+    pub(crate) fn __assert_debug_fmt<T: Debug>(
+        left: &T,
+        right: &T,
+        args: Option<fmt::Arguments<'_>>,
+    ) {
+        let (left, right) = (format!("{left:#?}"), format!("{right:#?}"));
+        if left != right {
+            panic!(
+                r#"assertion failed: `("{{left:#?}}" == "{{right:#?}}")`{}
+
+{}
+"#,
+                match args {
+                    Some(args) => format!(": {args}"),
+                    None => "".to_owned(),
+                },
+                StrComparison::new(&left, &right),
+            );
+        }
+    }
+}
diff --git a/crates/voicevox_core/src/publish.rs b/crates/voicevox_core/src/publish.rs
index 41e1b8805..fd0a409e9 100644
--- a/crates/voicevox_core/src/publish.rs
+++ b/crates/voicevox_core/src/publish.rs
@@ -651,6 +651,7 @@ fn list_windows_video_cards() {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::macros::tests::assert_debug_fmt_eq;
     use pretty_assertions::assert_eq;
     use test_util::OPEN_JTALK_DIC_DIR;
 
@@ -661,7 +662,7 @@ mod tests {
             .lock()
             .unwrap()
             .initialize(InitializeOptions::default());
-        assert_eq!(Ok(()), result);
+        assert_debug_fmt_eq!(Ok(()), result);
         internal.lock().unwrap().finalize();
         assert_eq!(
             false,
@@ -695,7 +696,7 @@ mod tests {
     ) {
         let internal = VoicevoxCore::new_with_mutex();
         let result = internal.lock().unwrap().load_model(speaker_id);
-        assert_eq!(expected_result_at_uninitialized, result);
+        assert_debug_fmt_eq!(expected_result_at_uninitialized, result);
 
         internal
             .lock()
@@ -706,9 +707,10 @@ mod tests {
             })
             .unwrap();
         let result = internal.lock().unwrap().load_model(speaker_id);
-        assert_eq!(
-            expected_result_at_initialized, result,
-            "got load_model result"
+        assert_debug_fmt_eq!(
+            expected_result_at_initialized,
+            result,
+            "got load_model result",
         );
     }
 
diff --git a/crates/voicevox_core/src/status.rs b/crates/voicevox_core/src/status.rs
index 309d060b8..4c4704bd2 100644
--- a/crates/voicevox_core/src/status.rs
+++ b/crates/voicevox_core/src/status.rs
@@ -359,6 +359,7 @@ impl Status {
 mod tests {
 
     use super::*;
+    use crate::macros::tests::assert_debug_fmt_eq;
     use pretty_assertions::assert_eq;
 
     #[rstest]
@@ -391,7 +392,7 @@ mod tests {
     fn status_load_metas_works() {
         let mut status = Status::new(true, 0);
         let result = status.load_metas();
-        assert_eq!(Ok(()), result);
+        assert_debug_fmt_eq!(Ok(()), result);
         let expected = BTreeSet::from([0, 1, 2, 3]);
         assert_eq!(expected, status.supported_styles);
     }
@@ -407,7 +408,7 @@ mod tests {
     fn status_load_model_works() {
         let mut status = Status::new(false, 0);
         let result = status.load_model(0);
-        assert_eq!(Ok(()), result);
+        assert_debug_fmt_eq!(Ok(()), result);
         assert_eq!(1, status.models.predict_duration.len());
         assert_eq!(1, status.models.predict_intonation.len());
         assert_eq!(1, status.models.decode.len());
@@ -422,7 +423,7 @@ mod tests {
             "model should  not be loaded"
         );
         let result = status.load_model(model_index);
-        assert_eq!(Ok(()), result);
+        assert_debug_fmt_eq!(Ok(()), result);
         assert!(
             status.is_model_loaded(model_index),
             "model should be loaded"