The present invention relates to a composition comprising ethyl vanillin or a pharmaceutically acceptable salt thereof as an effective ingredient for preventing or treating muscle disease or for improving a muscle function. Having the capability of upregulating the expression of a protein associated with muscle protein synthesis and muscle mass increase in myocytes and downregulating at an mRNA level the expression of an enzyme involved in muscle protein degradation, ethyl vanillin can exhibit effects of muscle differentiation, muscle regeneration, and muscle strengthening through an increase in muscle mass against muscle diseases attributed to muscle function decrease, muscle consumption, or muscle degradation and can suppress sarcopenia. Thus, ethyl vanillin can be used for preventing or treating muscle diseases or for promoting muscle differentiation, muscle regeneration and muscle strengthening, muscle mass increase, or muscle generation or for improving muscle function.