Novel azo compounds having the specific structural formula (1) or (3) set out below, water-soluble dyes containing the compounds, and polarizing films containing the water-soluble dyes: ##STR1## wherein R.sub.1 represents a hydrogen or halogen atom or a hydroxyl, C.sub.1-2 alkyl, C.sub.1-2 alkoxyl, C.sub.1-2 acylamino, cyano, carboxyl or sulfonic acid group; R.sub.3 and R.sub.8 individually represent a hydrogen atom or a hydroxyl, C.sub.1-2 alkyl or C.sub.1-2 alkoxyl group; R.sub.2 and R.sub.4 individually represent a hydrogen atom or a hydroxyl, C.sub.1-2 alkyl, C.sub.1-2 alkoxyl or C.sub.1-2 acylamino group; R.sub.5 represents a hydrogen atom or a carboxyl or C.sub.1-2 alkoxyl group; R.sub.6 represents a hydrogen atom, a hydroxyl, amino, methylamino, .beta.-hydroxyethylamino or C.sub.1-2 acylamino group, or a phenylamino or benzoylamino group which the phenyl nucleus may be substituted by one or more nitro, amino, hydroxyl, C.sub.1-2 alkyl, carboxyl and/or sulfonic acid groups and/or chlorine atoms; R.sub.7 represents a hydroxyl or amino group and substitutes at o- or p-position relative to the azo group; m stands for 0 or 1; p stands for 0 or 1; q stands for 0, 1 or 2; and M represents a copper, nickel, zinc and iron atom.