The present invention relates to a pharmaceutical composition containing Kaempferia parviflora Wall. Ex. Baker extracts for treating muscle diseases, and more specifically to a pharmaceutical composition containing, as an active ingredient, Kaempferia parviflora Wall. Ex. Baker extracts or flavone compound isolated therefrom for treating muscle diseases or a dietary composition for improving muscle function. Kaempferia parviflora Wall. Ex. Baker extracts or flavone compound isolated therefrom according to the present invention reduces protein catabolism in the muscles and increases muscle cell differentiation and anabolism, and is thus effective for preparing pharmaceutical composition for treating muscle diseases and dietary composition for improving muscle function.