diff --git a/LEGAL b/LEGAL
index 8080cfef61..d5dfef033c 100644
--- a/LEGAL
+++ b/LEGAL
@@ -593,28 +593,6 @@ ext/digest/sha2/sha2.[ch]:
     OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     SUCH DAMAGE.
 
-ext/json/generator/generator.c:
-
-    Copyright 2001-2004 Unicode, Inc.
-
-    Disclaimer
-
-    This source code is provided as is by Unicode, Inc. No claims are
-    made as to fitness for any particular purpose. No warranties of any
-    kind are expressed or implied. The recipient agrees to determine
-    applicability of information provided. If this file has been
-    purchased on magnetic or optical media from Unicode, Inc., the
-    sole remedy for any claim will be exchange of defective media
-    within 90 days of receipt.
-
-    Limitations on Rights to Redistribute This Code
-
-    Unicode, Inc. hereby grants the right to freely use the information
-    supplied in this file in the creation of products supporting the
-    Unicode Standard, and to make copies of this file in any form
-    for internal or external distribution as long as this notice
-    remains attached.
-
 ext/nkf/nkf-utf8/config.h:
 ext/nkf/nkf-utf8/nkf.c:
 ext/nkf/nkf-utf8/utf8tbl.c:
diff --git a/common.mk b/common.mk
index 3f4bcf6c3a..6c5bea5402 100644
--- a/common.mk
+++ b/common.mk
@@ -814,8 +814,7 @@ EXT_SRCS = $(srcdir)/ext/ripper/ripper.c \
 
 srcs-ext: $(EXT_SRCS)
 
-srcs-extra: $(srcdir)/ext/json/parser/parser.c \
-	    $(srcdir)/ext/date/zonetab.h \
+srcs-extra: $(srcdir)/ext/date/zonetab.h \
 	    $(empty)
 
 LIB_SRCS = $(srcdir)/lib/unicode_normalize/tables.rb
@@ -911,11 +910,6 @@ $(srcdir)/ext/ripper/ripper.c: $(srcdir)/parse.y id.h
 		Q=$(Q) ECHO=$(ECHO) RM="$(RM)" top_srcdir=../.. srcdir=. VPATH="$(PWD)" \
 		RUBY="$(BASERUBY)" PATH_SEPARATOR="$(PATH_SEPARATOR)"
 
-$(srcdir)/ext/json/parser/parser.c: $(srcdir)/ext/json/parser/parser.rl
-	$(ECHO) generating $@
-	$(Q) $(CHDIR) $(@D) && $(exec) $(MAKE) -f prereq.mk $(MFLAGS) \
-		Q=$(Q) ECHO=$(ECHO) top_srcdir=../../.. srcdir=. VPATH=../../.. BASERUBY="$(BASERUBY)"
-
 $(srcdir)/ext/date/zonetab.h: $(srcdir)/ext/date/zonetab.list
 	$(ECHO) generating $@
 	$(Q) $(CHDIR) $(@D) && $(exec) $(MAKE) -f prereq.mk $(MFLAGS) \
diff --git a/doc/maintainers.rdoc b/doc/maintainers.rdoc
index d22d09f7a4..ec6a6b7134 100644
--- a/doc/maintainers.rdoc
+++ b/doc/maintainers.rdoc
@@ -209,8 +209,6 @@ Zachary Scott (zzak)
   Nobuyuki Nakada (nobu)
 [ext/io/wait]
   Nobuyuki Nakada (nobu)
-[ext/json]
-  NARUSE, Yui (naruse)
 [ext/mathn/complex]
   Keiju ISHITSUKA (keiju)
 [ext/mathn/rational]
diff --git a/ext/.document b/ext/.document
index 2e6fc78879..f5da0912ed 100644
--- a/ext/.document
+++ b/ext/.document
@@ -35,9 +35,6 @@ io/console/console.c
 io/nonblock/nonblock.c
 io/wait/lib
 io/wait/wait.c
-json/ext/generator/generator.c
-json/ext/parser/parser.c
-json/lib
 mathn/complex/complex.c
 mathn/rational/rational.c
 nkf/lib
diff --git a/ext/Setup b/ext/Setup
index 0929d647ae..7d5e99bca7 100644
--- a/ext/Setup
+++ b/ext/Setup
@@ -20,9 +20,6 @@
 #io/console
 #io/nonblock
 #io/wait
-#json
-#json/generator
-#json/parser
 #mathn/complex
 #mathn/rational
 #nkf
diff --git a/ext/Setup.nacl b/ext/Setup.nacl
index eb8a1a70cd..4b1cca1392 100644
--- a/ext/Setup.nacl
+++ b/ext/Setup.nacl
@@ -22,9 +22,6 @@
 # io/console
 # io/nonblock
 # io/wait
-# #json
-# json/generator
-# json/parser
 # mathn/complex
 # mathn/rational
 # nkf