The invention provides a methioninase inhibitor to suppress the production of methyl mercaptan that is a causative substance of a bad smell by inhibiting methioninase originated from bacteria, as well as a composition and a food or drink containing the same, wherein the methioninase inhibitor contains an extract obtained from a plant of the family Myrsinaceae, genus Myrsine, preferably Myrsine seguinii as an active ingredient; and further provides a methioninase inhibitor, as well as a composition and a food or drink containing the same, wherein the methioninase inhibitor contains as an active ingredient one or more selected from the group consisting of myrsinoic acid A, myrsinoic acid B, myrsinoic acid C, myrsinoic acid E and myrsinoic acid F; preferably the myrsinoic acid A, myrsinoic acid B, myrsinoic acid C, myrsinoic acid E and myrsinoic acid F are obtained from a plant of the family Myrsinaceae, genus Myrsine, preferably Myrsine seguinii.