Disclosed herein are substituted vinylurea derivatives represented by the following general formula (1): ##STR1## wherein R.sup.1 and R.sup.3 are independently a phenyl group which may be substituted, R.sup.2 is a phenyl group which may be substituted, or a cycloalkyl group, and wave lines mean that the bonding state may be either E or Z, with the proviso that the cases where R.sup.1, R.sup.2 and R.sup.3 are unsubstituted phenyl groups, and where R.sup.1 and R.sup.2 are unsubstituted phenyl groups and R.sup.3 is a 4-ethoxyphenyl group are excluded, or salt thereof, and medicines comprising such a derivative as an active ingredient as well as a method of preventing and treating arteriosclerosis with such a medicine. The derivatives or salts thereof selectively and strongly inhibit ACAT in macrophages and are hence useful as prophylactic and therapeutic agents for arteriosclerosis.