diff --git a/lib/doc/ja/Math.lyx b/lib/doc/ja/Math.lyx
index 457c0f41c0..9f7a20c478 100644
--- a/lib/doc/ja/Math.lyx
+++ b/lib/doc/ja/Math.lyx
@@ -36993,7 +36993,7 @@ status collapsed
 \begin_inset CommandInset href
 LatexCommand href
 name "取扱説明書"
-target "http://www.tug.org/applications/hyperref/ftp/doc/manual.pdf"
+target "http://www.ctan.org/tex-archive/macros/latex/contrib/mhchem/mhchem.pdf"
 literal "false"
 
 \end_inset