Provided is a reflection film for a backlight optical system as a constituent of a display having a high quality by preventing damage on a light guiding plate, especially a polyolefin-based light guiding plate, with intrinsic performances of the reflection film such as an optical characteristic, a blocking property, tractability and the like sustained. A reflection film used in a backlight optical system consisting of a light source, a light guiding plate and a reflection film, wherein a resin layer containing particles with elasticity is provided on a surface, in contact with the light guiding plate, of the reflection film. The reflection film contains particles with elasticity therein. It is preferable that the particles with elasticity each have a cushioning property and elasticity and a rubber hardness (JIS K6253) of 50 or less. Specifically, the particles with elasticity each are preferably made of silicone, crosslinked polyacrylate ester, polyurethane or the like. The diameters of the particles with elasticity are preferably in the range of from 1 to 60 μm.