The present invention relates to a reflector for a back light assembly and a back light assembly using the same. A reflector for a back light assembly for use in an LCD device comprises a base film; a protrusion of elastic material provided on a surface of the base film; and a reflecting layer deposited on the base film and the elastic protrusion, for reflecting light. With this configuration, the back light assembly prevents damage or deformation due to friction or impact between a light guide plate and the reflector and enhances the brightness of an LCD device.