Triphenylmethane-based colored composition

A polymer having a monomer unit derived from the compound represented by the following general formula (1):

• wherein R1 to R4 each independently represent a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, a sulfoalkyl group having 1 to 6 carbon atoms, a carboxyalkyl group having 2 to 7 carbon atoms, a cyanoalkyl group having 2 to 7 carbon atoms, an alkoxyalkyl group having 2 to 6 carbon atoms, a halogenated alkyl group having 1 to 6 carbon atoms, or a phenyl group, a naphthyl group or a benzyl group, having a substituent or not having a substituent;
• R5 to R7 each independently represent a hydrogen atom or a methyl group;
• n pieces of R8 each independently represent a halogen atom, an alkyl group having 1 to 21 carbon atoms, an aryl group having 6 to 10 carbon atoms, a hydroxy group, a nitro group, a sulfo group, or an alkoxy group having 1 to 3 carbon atoms;
• n represents an integer of 0 to 4;
• A1 represents an alkylene group having 1 to 21 carbon atoms, which has at least one group selected from —O—, —OCO—, —COO— and an arylene group in the chain, an alkylene group having 1 to 21 carbon atoms, which has at least one group selected from —O—, —OCO—, —COO— and an arylene group in the chain, and also has a hydroxy group as a substituent, an alkylene group having 1 to 21 carbon atoms which has a hydroxy group as a substituent, or an alkylene group having 1 to 21 carbon atoms;
• A2 represents —NH— or —O—;
• and An− represents an anion containing an aryl group having an electron-withdrawing substituent, a sulfonyl group having an electron-withdrawing substituent, or a halogenated alkyl group.