The present invention provides Cephem compounds which have a wide antimicrobial spectrum and have potent antimicrobial activity against beta-lactamase producing Gram negative bacteria as follows: A compound of the formula: wherein, X is N, CH or C-Cl； T is S or the like； A and G are lower alkylene or the like； B is a single bond or the like； D is a single bond, -NR 7 -, -CO-, -CO-NR 7 -, -NR 7 -CO-, -NR 7 -CO-NR 7 -, or the like； E is optionally substituted lower alkylene； F is a single bond or optionally substituted phenylene； R 3 , R 4 , R 5 and R 6 each is independently hydrogen, halogene, nitrile, or the like； or an ester, a compound protected at the amino on the ring in the 7-side chain, a pharmaceutically acceptable salt, or a solvate thereof.
