PURPOSE: To provide a new compd. which possesses excellent light fastness and pH stability and is useful for colorants and the like in thermal or pressure- sensitive recording materials and the like.

CONSTITUTION: This chromogenic lactam is a compd. represented by formula I [wherein ring A represents a (hetero) arom. group; ring B represents a (substd.) benzene nucleus; Z represents O, or NR (wherein R represents H, a lower alkyl, 5-10C cycloalkyl or the like); R1 to R3 each represent H, a lower alkyl, lower alkoxy or the like; R4 to R6 each represent H, a halogen, cyano, nitro, lower alkyl or the like; X1 and X2 each represent H, a (substd.) alkyl, 1-8C acyl, 5-10C cycloalkyl or the like], e.g. 10-dimethylamino-12b-(4'- dimethylaminophenyl)-2,7,8,12b-tetrahydroisoindolo[1,2-a]3,1-benzoxazine-2,8-dione. The compd. represented by formula I may be obtd., e.g. by reacting a keto acid represented by formula II with a difunctional amino compd. represented by formula III.