The present invention relates to a composition for preventing or treating heart disease, and more particularly, to a composition for preventing or treating heart disease, comprising (+)-syringaresinol. Specifically, (+)-syringaresinol as an active ingredient may exhibit excellent effect of preventing or improving heart disease by promoting SIRT1 expression and suppressing death of cardiomyocytes induced by reactive oxygen species. Accordingly, the composition according to the present disclosure may be used to prevent, improve or treat heart diseases including cardiovascular diseases.