The present invention relates to a benzazepinone compound represented by thefollowing formula (I):(see formula I)wherein R1 represents a C1-C6 alkyl group or halogeno C1-C6 alkyl group, R2representsa carboxyl group which may be protected, and Y represents a group representedby theformula (II):(see formula II)wherein Z represents CH or a nitrogen atom,or a pharmaceutically acceptable salt thereof.