The purpose of the present invention is to provide a medicament which is useful for prevention or treatment of muscle injury. The present invention relates to a novel medical use of an extract from inflamed tissues inoculated with vaccinia virus, and more particularly, it relates to a preventing or therapeutic agent for muscle injury containing the extract as an active ingredient. The preventing or therapeutic agent for muscle injury of the present invention containing the extract as an active ingredient is extremely useful as a highly effective and highly safe medicament.
