The object is to provide prasugrel hydrochloride or the like having a reduced CATP content. Specifically disclosed is a process for producing prasugrel hydrochloride shown by the scheme below, wherein the temperature at which a chlorinating agent is added dropwisely or added in step (i) and the reaction temperature after the dropwise addition or addition of the chlorinating agent are adjusted to lower temperatures. Step i Step ii Step iii Step iv wherein R represents a protective group for a hydroxy group.
