The purpose of this study was to determine the effectiveness of yuzu peels for preventing nonalcoholic fatty liver disease. We investigated the effect of yuzu (Citrus junos) peel extract (YPE) on fatty liver steatosis induced by a high-sucrose diet in rats. Rats fed a high-sucrose diet supplemented with 2% (w/w) YPE showed suppression of fat accumulation in the liver, compared with rats fed a high-sucrose diet alone. The functional components of YPE were analyzed by GC-MS/MS. Rats were then fed a high-sucrose diet supplemented with candidate substances detected in the YPE. Among the substances tested, myo-inositol was determined to be one of the functional components. Metabolomic analyses were performed to clarify the mechanism of action of myo-inositol in the suppression of fat accumulation in the liver. The levels of two fatty acids, myristate and oleate, were found to increase following the intake of a high-sucrose diet, but their levels were significantly decreased following the intake of a high-sucrose diet supplemented with myo-inositol. The results suggest that the functional component of YPE is myo-inositol. Additionally, myo-inositol suppressed the biosynthesis of fatty acids enhanced by the high-sucrose diet.