A novel compound represented by the formula (1): ##STR00001## [R.sup.1 represents hydrogen atom, chlorine atom, or hydroxyl group; X.sup.1 . . . X.sup.2 represents--CH(R.sup.2)--CH(R.sup.3)--, --CH(R.sup.2)--CH(R.sup.3)--CH(R.sup.4)--, etc.; R.sup.2 to R.sup.4represent hydrogen atom, or an alkyl group; A.sup.1, A.sup.11, A.sup.2, and A.sup.21 represent hydrogen atom, or an alkyl group; Y represents --CH(A.sup.3)--, --CH(A.sup.3)--C(A.sup.4)(A.sup.41)--, --CH(A.sup.3)--C(A.sup.4)(A.sup.41)--C(A.sup.5)(A.sup.51)--, or a single bond; A.sup.3, A.sup.4, A.sup.41, A.sup.5, and A.sup.51 represent hydrogen atom, or an alkyl group; Z represents hydroxyl group, or --N(A.sup.6)(A.sup.61); A.sup.6 represents hydrogen atom, or an alkyl group, A.sup.61 represents hydrogen atom, an alkyl group, an aralkyl group, etc.; and groups in each of one or more combinations selected from the group consisting of combinations of A.sup.6 and A.sup.3, A.sup.6 and A.sup.4, A.sup.6 and A.sup.1, A.sup.6 and A.sup.2, A.sup.2 and A.sup.3, A.sup.2 and A.sup.4, A.sup.6 and A.sup.5, A.sup.3 and A.sup.1, and A.sup.5 and A.sup.1 may bind to each other to form a 5- or 6-membered ring], or a salt thereof, which potently inhibits the phosphorylation of myosin regulatory light chain.