The present invention provides a polyolefin/polyester-based reflective film having a high reflectivity and a reflective sheet for backlight comprising the reflective film, wherein the reflective film is produced by forming a resin composition that contains 100 parts by mass of a polyolefin component (A) comprising a polyolefin with stereospecificity and a modified polypropylene and from 40 to 240 parts by mass of a biodegradable polyester component (B), into a film followed by stretching it, and wherein the reflective film requires neither addition of a filler to the starting resin composition nor provision of a reflective coating layer on the surface of the resulting film for the purpose of imparting optical properties such as reflectivity to the film.