A protective film for polarizing plate made by laminating k layers (k being an integer of 2 to 7) of thermoplastic resin, in which a refractive index ni(λ) at a wavelength X in the range of 380 to 780 nm of the i th thermoplastic resin layer as well as a refractive index ni+1(λ) at a wavelength λin the range of 380 to 780 nm of the i+1 th thermoplastic resin layer have a relationship of In |ni(λ)−ni+1(λ)|≦0.045 (i being an integer of 1 to k−l); and a polarizing plate comprising the protective film and a polarizer. The protective film has an in-plane retardation Re at a wavelength λof 550 nm of 50 nm or less, and is obtained by coextruding at least one layer (A) of thermoplastic resin having of a negative photoelastic coefficient with at least one layer (B) of thermoplastic resin having a positive photoelastic coefficient.