Abstract: 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.