The present invention provides a pharmaceutical composition for use in treating an intractable heart tissue fibrosis disease accompanied by chronic heart failure. The pharmaceutical composition for use in treating an intractable heart tissue fibrosis disease accompanied by chronic heart failure comprises, as an active ingredient, at least one member selected from the group consisting of protease inhibitors, thromboxane A2 synthase inhibitors, thromboxane A2 synthase antagonists, phosphodiesterase (PDE) inhibitors, tyrosine kinase inhibitors, HMG-CoA reductase inhibitors, and antifibrotic agents. (The pharmaceutical composition includes biodegradable polymer-encapsulated, long-acting preparations thereof.)
