diff --git a/pages/background.js b/pages/background.js
index 85e38ad..4e036e2 100644
--- a/pages/background.js
+++ b/pages/background.js
@@ -22,6 +22,7 @@ var defaultOptions = {
     // Keyboard Settings
     keyboardSupport   : true,  // option
     arrowScroll       : 50,    // [px]
+    spaceScroll       : 0.9,   // decimal
 
     // Other
     touchpadSupport   : true,
diff --git a/pages/options.html b/pages/options.html
index 3f0358f..f610b78 100755
--- a/pages/options.html
+++ b/pages/options.html
@@ -242,6 +242,12 @@ <h2 style="margin-top:0;">Scroll Settings</h2>
   <td class="default_value"><span style="color: #00CCFF; font-size: 12px;"> <i>Default value: 4</i></span></td>
   <td class="note" title="it affects how long the decceleration part is">(<b>ratio </b>of "tail" to "acceleration")</td>
 </tr>
+ <tr>
+  <td class="setting-name"><label for="spaceScroll" title="higher means more scrolling for each spacebar key press">Spacebar step size</label></td>
+  <td><input id="spaceScroll" type="text" size="1" maxlength="3"></td>
+  <td class="default_value"><span style="color: #00CCFF; font-size: 12px;"> <i>Default value: 0.9</i></span></td>
+  <td class="note" title="higher means more scrolling for each spacebar key press">(<b>how</b> much with spacebar)</td>
+ </tr>
  <tr>
   <td style="width:180px;"><label for="arrowScroll" title="higher means more scrolling for each arrow key press">Arrow key step size [px]</label></td>
   <td><input id="arrowScroll" type="text" size="1" maxlength="3"> </td>
diff --git a/pages/options.js b/pages/options.js
index d743c38..b519bc8 100644
--- a/pages/options.js
+++ b/pages/options.js
@@ -11,6 +11,7 @@ var optionsList = [
   'animationTime',
   'stepSize',
   'arrowScroll',
+  'spaceScroll',
   'middleMouse',
   'accelerationMax',
   'accelerationDelta',
diff --git a/src/sscr.js b/src/sscr.js
index 962f443..0cc4d3e 100755
--- a/src/sscr.js
+++ b/src/sscr.js
@@ -28,6 +28,7 @@ var defaultOptions = {
     // Keyboard Settings
     keyboardSupport   : true,  // option
     arrowScroll       : 50,     // [px]
+    spaceScroll       : 0.9,    // decimal
 
     // Other
     touchpadSupport   : false,
@@ -427,7 +428,7 @@ function keydown(event) {
             break;         
         case key.spacebar: // (+ shift)
             shift = event.shiftKey ? 1 : -1;
-            y = -shift * clientHeight * 0.9;
+            y = -shift * clientHeight * options.spaceScroll;
             break;
         case key.pageup:
             y = -clientHeight * 0.9;