A cathode ray tube for producing images in red, green or blue is used for a projection type television set. A multi-layered interference filter is disposed between a face glass and a fluroescent layer so as to gather light beams from the fluorescent layer. The innermost layer of the interference layer is made of a high refractive index material such as tantalum pentaoxide which is resistant to hydrofluoric acid, so that a fluorescent material can be applied as efficiently as possible. The innermost layer of the interference filter has the optical distance expressed by the equation:nd=(2m+1).lambda..sub.h /4.lambda..sub.h =.lambda.+.lambda..sub.pwhere n stands for the refractive index of the layer, d stands for thickness of the layer, m stands for an integer larger than 0, .lambda..sub.h is the cutoff wavelength of the optical spectrum transmissitivity of the multi-layered interference film for yielding a transmissivity of fifty percent and .lambda..sub.p is 20 to 100 nm. The innermost layer is made thick so as to be resistant to hydrofluoric acid.