A benzothiadiazine derivative, hydrate thereof and acid addition salt thereof, the derivative being represented by the general formula (I) ##STR1## wherein X is methylene or a nitrogen atom substituted with a lower alkyl, Y and Z are each methylene or carbonyl, A is phenylene or phenylene substituted with methoxycarbonyl, R.sub.4 is lower alkylene or lower alkenylene, R.sub.1 is a hydrogen atom, acetoxyacetyl, cyclohexylmethyl or benzyl wherein the benzene ring may be substituted with lower alkoxyl, halogen atom, nitro, lower alkyl, methylenedioxy or hydroxyl, R.sub.2 is lower alkyl or phenyl, and R.sub.3 is a hydrogen atom, halogen atom or lower alkoxyl with the exception of the case where X, Y and Z are each methylene, A is unsubstituted phenylene, R.sub.4 is lower alkylene and R.sub.1 is a hydrogen atom; and a peptic ulcer treating agent containing as an effective component the above derivative, hydrate thereof or acid addition salt thereof.