diff --git a/ChangeLog b/ChangeLog
index 6ed66c2a86..58fd2da365 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+Thu Jun 20 15:14:00 2013  Koichi Sasada  <ko1@atdot.net>
+
+	* benchmark/gc: create a directory to store GC related benchmark.
+
+	* benchmark/gc/gcbench.rb: moved from tool/gcbench.rb.
+
+	* benchmark/gc/hash(1|2).rb: ditto.
+
+	* benchmark/gc/rdoc.rb: ditto.
+
+	* benchmark/gc/null.rb: added.
+
+	* common.mk: fix rule.
+
 Thu Jun 20 14:09:54 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* tool/hashbench1.rb: fix paramter too. Increase temporary objects.
diff --git a/tool/gcbench.rb b/benchmark/gc/gcbench.rb
similarity index 67%
rename from tool/gcbench.rb
rename to benchmark/gc/gcbench.rb
index ca9f3cd950..5fee2a2bce 100644
--- a/tool/gcbench.rb
+++ b/benchmark/gc/gcbench.rb
@@ -2,7 +2,11 @@
 require 'benchmark'
 require 'pp'
 
-script = ARGV.shift || raise
+script = File.join(__dir__, ARGV.shift)
+script += '.rb' unless FileTest.exist?(script)
+raise "#{script} not found" unless FileTest.exist?(script)
+
+puts "Script: #{script}"
 
 GC::Profiler.enable
 tms = Benchmark.measure{|x|
@@ -14,6 +18,7 @@ pp GC.stat
 gc_time = GC::Profiler.total_time
 
 puts
+puts script
 puts Benchmark::CAPTION
 puts tms
 puts "GC total time (sec): #{gc_time}"
diff --git a/tool/hashbench1.rb b/benchmark/gc/hash1.rb
similarity index 100%
rename from tool/hashbench1.rb
rename to benchmark/gc/hash1.rb
diff --git a/tool/hashbench2.rb b/benchmark/gc/hash2.rb
similarity index 100%
rename from tool/hashbench2.rb
rename to benchmark/gc/hash2.rb
diff --git a/benchmark/gc/null.rb b/benchmark/gc/null.rb
new file mode 100644
index 0000000000..31c18878b5
--- /dev/null
+++ b/benchmark/gc/null.rb
@@ -0,0 +1 @@
+# null
diff --git a/benchmark/gc/rdoc.rb b/benchmark/gc/rdoc.rb
new file mode 100644
index 0000000000..14c89f5611
--- /dev/null
+++ b/benchmark/gc/rdoc.rb
@@ -0,0 +1,13 @@
+require 'rdoc/rdoc'
+require 'tmpdir'
+
+srcdir = File.expand_path('../..', __dir__)
+
+Dir.mktmpdir('rdocbench-'){|d|
+  dir = File.join(d, 'rdocbench')
+  args = %W(--root #{srcdir} --page-dir #{srcdir}/doc --encoding=UTF-8 --no-force-update --all --ri --debug --quiet #{srcdir})
+  args << '--op' << dir
+
+  r = RDoc::RDoc.new
+  r.document args
+}
diff --git a/common.mk b/common.mk
index 83e6ce7599..88043575d0 100644
--- a/common.mk
+++ b/common.mk
@@ -426,19 +426,13 @@ rdoc-coverage: PHONY main
 
 RDOCBENCHOUT=/tmp/rdocbench
 
+GCBENCH_ITEM=null
+
+gcbench: PHONY
+	$(Q) $(XRUBY) "$(srcdir)/benchmark/gc/gcbench.rb" $(GCBENCH_ITEM)
+
 gcbench-rdoc: PHONY
-	@echo Benchmark with Generating RDoc documentation
-	$(Q) $(XRUBY) "$(srcdir)/tool/gcbench.rb" "$(srcdir)/tool/rdocbench.rb" --root "$(srcdir)" --page-dir "$(srcdir)/doc" --encoding=UTF-8 --no-force-update --all --ri  --debug $(RDOCFLAGS) --quiet "$(srcdir)"
-
-gcbench-hash1: PHONY
-	@echo "Benchmark with hashbench1 (many temporal objects / obj count intensive)"
-	$(Q) $(XRUBY) "$(srcdir)/tool/gcbench.rb" "$(srcdir)/tool/hashbench1.rb"
-
-gcbench-hash2: PHONY
-	@echo "Benchmark with hashbench2 (increasing hash size / malloc intensive)"
-	$(Q) $(XRUBY) "$(srcdir)/tool/gcbench.rb" "$(srcdir)/tool/hashbench2.rb"
-
-gcbench-hash: PHONY gcbench-hash1 gcbench-hash2
+	$(Q) $(XRUBY) "$(srcdir)/benchmark/gc/gcbench.rb" rdoc
 
 nodoc: PHONY
 
diff --git a/tool/rdocbench.rb b/tool/rdocbench.rb
deleted file mode 100644
index a248b9a9b7..0000000000
--- a/tool/rdocbench.rb
+++ /dev/null
@@ -1,11 +0,0 @@
-require 'rdoc/rdoc'
-require 'tmpdir'
-
-Dir.mktmpdir('rdocbench-'){|d|
-  dir = File.join(d, 'rdocbench')
-  args = ARGV.dup
-  args << '--op' << dir
-
-  r = RDoc::RDoc.new
-  r.document args
-}