PROBLEM TO BE SOLVED: To provide a toxin production inhibitor for microorganisms capable of suppressing toxin production without disturbing proliferation of microorganisms.SOLUTION: This toxin production inhibitor for microorganisms includes one or more kinds of compounds (A) selected from compounds represented by general formula (1): RO-[(EO)m(PO)n]-H (1). (In the formula, R represents a 8-18C hydrocarbon group, EO represents an ethyleneoxy group, PO represents a propyleneoxy group, m and n each represent an average addition mole number, and inequalities 0≤m<20, 0