A protective film for polarizing plates comprises an antireflection layer (reflectance.ltoreq.0.5% at 550 nm) having high refractivity layers and low refractivity layers alternately laminated on a thermoplastic film (photoelastic coefficient.ltoreq.9.0.times.10.sup.-12 Pa.sup.-1, saturated water absorption<0.05% by weight) and has 0.3 or smaller standard deviation of S, which is obtained by obtaining a reflectance R(.lamda.) at a wavelength .lamda. while .lamda. is increased from 380 to 780 nm by an increment .DELTA..lamda. of 1 nm, calculating S:.lamda..times..DELTA..times..times..lamda..function..lamda. ##EQU00001## and calculating the standard deviation at 10 points randomly selected within 100 cm.sup.2 on the surface of the film. When the film is disposed on the surface of the visual side of a display device such as a liquid crystal display device, the film prevents reflection and suppresses fluctuation in distributions of luminance and color difference due to the uniform spectral reflectance within the surface of the film.