The object of the invention is to provide a new composition for suppressing fatty degeneration of a muscle, the composition including a component that is safe and suitable for a long term intake. It was found that quercetin or a glycoside thereof suppresses a differentiation process from myosatellite cells into adipocyte-like cells. In the present invention, quercetin or a glycoside thereof is used in a composition for suppressing fatty degeneration of a muscle.
