The present invention provides a biaxially oriented film of a polylactic acid resin that is suitable for films for bags and packaging films for various windows, particularly films for outlook window envelopes. The film is biodegradable and, as films for outlook window envelopes, is superior in the coating adaptability for an antistatic agent, a lubricant and an antiblocking agent or the like and in the high-speed cutting property.The present invention discloses a biaxially oriented film of a polylactic acid resin comprising not less than 50% by weight of a polylactic acid resin, which has a storage modulus E'at 80.degree. C. within the range from 10 MPa to 3,000 MPa, as determined by the test method for temperature dependency of dynamic viscoelasticity, in accordance with JIS K7198 (method A); a heat shrinkage of not higher than 10%, upon heating at 80.degree. C. for 10 seconds; and a tear strength in the width direction (TD direction) of the film of 10 to 200 mN, as determined in accordance with JIS K7128 (method B).