Benzimidazole derivatives of the formula (I): ##STR1## wherein the ring A is a benzene ring which may optionally contain substitution in addition to the R' group; R.sup.1 is hydrogen or an optionally substituted hydrocarbon residue; R.sup.2 is a group capable of forming an anion or a group convertible thereinto; X is a direct bond or a spacer having an atomic length of two or less between the phenylene group and the phenyl group; R' is carboxyl, an ester thereof, an amide thereof or a group capable of forming an anion or convertible to an anion; Y is --O--, --S(O).sub.m -- or --N(R.sup.4)-- wherein m is an integer of 0, 1 or 2 and R.sup.4 is hydrogen or an optionally substituted alkyl group; and n is an integer of 1 or 2; and the pharmaceutically acceptable salts thereof, have potent angiotensin II antagonistic activity and antihypertensive activity, thus being useful as therapeutic agents for treating circulatory system diseases such as hypertensive diseases, heart diseases (e.g. hypercardia, heart failure, cardiac infarction, etc.), strokes, cerebral apoplexy, nephritis, etc.