The benzazole compounds of this invention can be represented by the following formula [I]: ##STR1## wherein R.sup.1 is aryl or a heterocyclic group, each of which may have suitable substitutent(s),R.sup.2 is hydroxy, mercapto, lower alkylthio, sulfo, lower alkyl, amino or substituted amino,R.sup.3 is hydrogen, halogen or lower alkoxy,A is lower alkenylene, lower alkylene optionally substituted with hydroxy, or a group of the formula:--A'--Q--A"--, in which A' is lower alkylene, A" is lower alkylene or a single bond, and Q is O or S, andX is O, S, NH or N--R.sup.4, in which R.sup.4 is lower alkyl,More particularly, it relates to benzazole compounds and pharmaceutically acceptable salts thereof which have antiulcer activity and H.sub.2 -receptor antagonism, to processes for the preparation thereof, to a pharmaceutical composition comprising the same and to a method for the treatment of ulcers in human being or animals.