An epoxy resin composition for optical sheets, the composition comprising a polyvalent carboxylic acid (A) represented by formula (I): wherein R1's each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group; q represents the number of substituent R1's, and represents an integer from 1 to 4; and P represents the following X: wherein there may be a plural number of R2's per ring, and R2's each independently represent a hydrogen atom or a methyl group; and * represents a bonding site linked to the oxygen atom; and an epoxy resin (B) having an aliphatic cyclic structure in the molecule.