PURPOSE: To obtain a cholecystokinin antagonistic agent containing a benzoxazepine compound and a benzothiazepine compound.

CONSTITUTION: This cholecystokinin antagonistic agent contains a compound of formula I or II [ring A is benzene ring or an aromatic heterocyclic ring; R1 is H or a hydrocarbon; R2 and R3 are each H or a hydrocarbon; X is a direct bond or a bivalent atomic chain; ring B is phenyl or an aromatic heterocyclic ring; Z is O or S(O)q; q is 0-2; ring B' is phenyl) or its salt as an active ingredient. The agent is effective in preventing and treating various symptoms caused by anxiety, psychosis, disorder in regulation of appetite, dysfunction of intestinal tract smooth muscle, pancreatitis, disorder in the gallbladder, gastric ulcer, duodenal ulcer, gastritis, regurgitant esophagitis, Zollinger-Ellison syndrome, pain. various syjnptoms, etc., induced by gastrin. The daily dose thereof for an adult is 1-500mg, preferably 10-20mg in the case of peroral administration.