A compound represented by the following formula (1) or a salt thereof: ##STR00001## wherein R.sup.1 represents hydrogen atom, a halogen atom and the like; R.sup.2 represents hydrogen atom, a halogen atom, a C.sub.1-6 alkyl group and the like; and R.sup.3 represents --O--X--C(A.sup.1)(A.sup.11)-C(A.sup.2)(A.sup.21)-N(A.sup.31)(A.sup.3) (X represents propylene group etc., A.sup.11 and A.sup.21 represent hydrogen atom, or a C.sub.1-6 alkyl group, A.sup.31 represents a C.sub.1-6 alkyl group substituted with hydroxyl group, or hydrogen atom, and A.sup.1, A.sup.2, and A.sup.3 represent hydrogen atom, a C.sub.1-6 alkyl group and the like) and the like, which has an inhibitory activity on the phosphorylation of myosin regulatory light chain, and is useful for treatment of diseases relating to contraction of various cells and the like.