A catalyst for producing monocyclic aromatic hydrocarbons, used for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon number from a feedstock oil having a 10 volume % distillation temperature of at least 140° C. and an end point temperature of not more than 400° C., wherein the catalyst contains a crystalline aluminosilicate, gallium and/or zinc, and phosphorus, the molar ratio between silicon and aluminum (Si/Al ratio) in the crystalline aluminosilicate is not more than 100, the molar ratio between the phosphorus supported on the crystalline aluminosilicate and the aluminum of the crystalline aluminosilicate (P/Al ratio) is not less than 0.01 and not more than 1.0, and the amount of gallium and/or zinc is not more than 1.2% by mass based on the mass of the crystalline aluminosilicate.