The present invention is directed to a pyrimidine derivative of the following formula (1) or a salt of the derivative: ##STR1## \x9bwherein R.sup.1 represents a hydroxyl group, a lower alkoxy group, a phenyloxy group which may have a substituent, an aralkyloxy group which may have a substituent, or --NR.sup.2 R.sup.3 ; X represents an oxygen atom or N--R.sup.4 ; m is 2 or 3; and n is 1 or 2 (wherein each of R.sup.2 and R.sup.3, which are identical to or different from each other, represents a hydrogen atom, a hydroxyl group, a lower alkyl group which may have a substituent, a phenyl group which may have a substituent, an aralkyl group which may have a substituent, or a heterocyclic group which may have a substituent; R.sup.4 represents a lower alkyl group, a phenyl group, a formyl group, or a lower alkoxycarbonyl group)!, as well as to a medicine containing the derivative or salt as the active ingredient. The compounds exhibit strong binding inhibitory activity against endothelin having potent vasoconstrictive effect. Therefore, the compounds are effective as remedies for various diseases including circulatory diseases.