Provided is a cephem compound which has a wide antimicrobial spectrum, and in particular exhibits potent antimicrobial activity against beta-lactamase producing Gram negative bacteria, and a pharmaceutical composition comprising the same. The cephem compound has the formula (I): where W and U are as defined in the specification; R1 is as defined in the specification; R2A and R2B are as defined in the specification, provided that R2A and R2B are not taken together to form an optionally substituted oxime group when R1 is aminothiazole or aminothiadiazole optionally protected at the amino group; ring A is a benzene ring or a 6-membered aromatic heterocyclic group having 1-3 nitrogen atoms; R3 is a hydrogen atom, —OCH3 or —NH—CH(═O); k is an integer from 0 to 2; R4 is as defined in the specification; and D and E are as defined in accordance with a) or b) described in the specification.