Disclosed is a process for producing an imidazothiazole derivative of formula (I) useful as an intermediate for the production of carbapenem derivatives having potent antimicrobial activity and a broad antimicrobial spectrum, that is, a novel method for nicotinoylating an imidazo[5,1-b]thiazole ring at its 7-position. The process comprises reacting a compound of formula (II) with a compound of formula (III).