The present invention provides a novel compound having a wide antibacterial spectrum and expressing strong antibacterial activity against beta lactamase producing gram negative bacteria in particular. This invention provides the compound represented by formula (I) (the meanings of the symbols are defined in the specification) or a protected product in which an amino group when the amino group exists on the ring in the 7 position side chain is protected a pharmaceutically acceptable salt of the compound or protected product and a pharmaceutical composition containing the same.