An object of the present invention is to provide prasugrel hydrochloride with a reduced content of CATP, and the like. In the formulae, R represents a protecting group for a hydroxyl group. A method for producing prasugrel hydrochloride represented by the above formula is provided, characterized by comprising, in step (i), controlling, at low values, the temperature during the addition, optionally dropwise, of a chlorinating agent and the reaction temperature after the addition, optionally dropwise, of the chlorinating agent.
