Provided are: a mold release film which has excellent mold releasability and is capable of reducing the contamination of a mold during a sealing step; a method for producing this mold release film; and a method for manufacturing a semiconductor package, which uses this mold release film. This mold release film is arranged on a surface of a mold, said surface coming into contact with a curable resin, during the production of a semiconductor package, wherein a semiconductor element is arranged within the mold and sealed with a curable resin, thereby forming a resin sealed part. This mold release film comprises a resin-side mold release layer, which comes into contact with the curable resin during the formation of the resin sealed part, and a gas barrier layer. The gas barrier layer contains at least one polymer (I) selected from the group consisting of polymers having a vinyl alcohol unit and polymers having a vinylidene chloride unit, and the gas barrier layer has a thickness of 0.1-5 [mu]m.