diff --git a/ext/date/date_parse.c b/ext/date/date_parse.c
index fcc9e33..ccbab09 100644
--- a/ext/date/date_parse.c
+++ b/ext/date/date_parse.c
@@ -3073,7 +3073,8 @@ static int
 jisx0301(VALUE str, VALUE hash)
 {
     static const char pat_source[] =
-        "\\A\\s*([" JISX0301_ERA_INITIALS "])?(\\d{2})\\.(\\d{2})\\.(\\d{2})"
+        "\\A\\s*([" JISX0301_ERA_INITIALS "])?"
+	"(\\d{2}|(?<=[" JISX0301_ERA_INITIALS "])\\d{3,})\\.(\\d{2})\\.(\\d{2})"
 	"(?:t"
 	"(?:(\\d{2}):(\\d{2})(?::(\\d{2})(?:[,.](\\d*))?)?"
 	"(z|[-+]\\d{2}(?::?\\d{2})?)?)?)?\\s*\\z";
diff --git a/test/date/test_date_parse.rb b/test/date/test_date_parse.rb
index cfe0b66..89fb34e 100644
--- a/test/date/test_date_parse.rb
+++ b/test/date/test_date_parse.rb
@@ -1075,6 +1075,16 @@ def test__jisx0301
     h = Date._jisx0301('R01.05.01')
     assert_equal([2019, 5, 1, nil, nil, nil, nil],
 		 h.values_at(:year, :mon, :mday, :hour, :min, :sec, :offset))
+    h = Date._jisx0301('R100.05.01')
+    assert_equal([2118, 5, 1, nil, nil, nil, nil],
+		 h.values_at(:year, :mon, :mday, :hour, :min, :sec, :offset))
+    h = Date._jisx0301('R100.05.01T04:05:06+09:00')
+    assert_equal([2118, 5, 1, 4, 5, 6, 32400],
+		 h.values_at(:year, :mon, :mday, :hour, :min, :sec, :offset))
+    h = Date._jisx0301('100.05.01')
+    assert_equal({}, h)
+    d = Date.new(2118, 5, 1)
+    assert_equal(d, Date.jisx0301(d.jisx0301))
 
     h = Date._jisx0301('H13.02.03T04:05:06')
     assert_equal([2001, 2, 3, 4, 5, 6, nil],