We investigated the effect of crocetin, a carotenoid present in the fruits of Gardenia jasminoides, on the improvement of lentigines in the skin and examined its mechanism of action. Subjects consumed an experimental meal consisting of a drink containing 7.5 mg of crocetin daily after dinner for 8 weeks. We examined the effects of oral ingestion of crocetin on the improvement of the size of lentigines on the skin. In an epidermis model in which crocetin was added at concentrations of 1 μg/mL and 2 μg/mL and cultured for 14 days, melanin was significantly suppressed compared with the control. Investigation of the mechanism of action via a cultured human epidermis model and cultured pigment cells revealed that crocetin decreased melanocortin receptor subtype 1 of melanocytes at the messenger ribonucleic acid level and inhibited the stimulatory action of melanocytes via melanocyte-stimulating hormone. The results of the study concluded that crocetin inhibits melanin synthesis by controlling the synthesis of tyrosinase and tyrosinase-related protein-1 via the suppression of melanocortin receptor subtype 1 expression.