PROBLEM TO BE SOLVED: To provide a cephem compound which has a strong antimicrobial activity, in particular effective against various &bgr-lactamase producing Gram negative bacteria, and a composition comprising the compound.SOLUTION: The present invention provides a pharmaceutical composition comprising a compound represented by formula (I), an ester at a carboxyl group, an amino-protected compound when the amino is present on a ring in the 7-side chain, or a pharmaceutically acceptable salt thereof.