The present invention provides agents having functions for inhibiting thickening of cardiac wall, agents for preventing cardiac failure containing the aforementioned agents, and functional foods promising effects for preventing cardiac failure. The agent for inhibiting thickening of cardiac wall of the present invention contains Xaa Pro Pro as an effective component.依據本發明而提供具有心臟壁肥厚抑制作用的藥劑、以及含有上述藥劑之心衰竭預防劑與可期待心衰竭預防效果的功能性食品。本發明之心臟壁肥厚抑制劑係包含Xaa Pro Pro作為有效成分。
