The present invention provides a medium for promoting muscle differentiation and a medium additive, a kit, and a pharmaceutical composition and dietary food for promoting muscle differentiation. These include ergothioneine, ascorbic acid 2-glucoside, ascorbic acid, and combinations of these components.本發明提供一種肌肉分化促進用培養基和培養基添加劑、套組、以及肌肉分化促進用醫藥組成物和飲食物,該等包含麥角硫因、抗壞血酸2-葡萄糖苷、抗壞血酸、及這些成分的組合。