A methine compound having a benzoxazole nucleus substituted by a meta-substituted aryl group and the methine compound represented by the following formula ##STR1## wherein R.sub.1 and R.sub.2 are the same or different and each represents a substituted or unsubstituted alkyl group; Z.sub.1 represents an atomic group necessary for forming a five-membered or six-membered nitrogen-containing heterocyclic ring; R.sub.3 represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, a halogen atom, a substituted or unsubstituted alkylthio group, or a substituted or unsubstituted heterocyclic group; L.sub.1, L.sub.2 and L.sub.3 are the same or different and each represents a substituted or unsubstituted methine group; n represents 0, 1, 2 or 3; M.sub.1 represents an ion for neutralizing charge; and m.sub.1 represents a number of 0 or more necessary for neutralizing the molecular charge.