A molding die for molding a molded article having a two-layer structure of a core and a foam layer, the molding die comprising a stationary die and a movable die for molding a molded article in a cavity defined between both of the dies (2,4), wherein the stationary die comprises a main die and a slide die that moves relative to the main die, the slide die partially faces the cavity and moves in a predetermined direction different from a die clamping and die opening direction; a face (32,33) of the slide die that faces the cavity comprises a plurality of faces (32,33) extending in a plurality of directions that are not mutually in parallel, wherein the plurality of faces (32,33) of the slide die include a face orthogonal to the die clamping and die opening direction and another face, wherein the main die comprises an accommodation space that accommodates the slide die partially or entirely; the accommodation space is molded so as to allow the slide die to move in the predetermined direction; the slide die is moved by an actuator so as to form a cavity for the foam layer in accordance with growth of the foam layer; the predetermined direction of the slide die is orthogonal to a combined vector determined by combining respective linear vectors, each respective linear vector being orthogonal to a respective one of the plurality of faces (32,33) extending in a plurality of directions making up the face of the slide die that faces the cavity and determined based on an area ratio of the respective face, one side face of the slide die is pushed out by an actuator, an inner wall of the movable die opposed to another side face of the slide die on the opposite side of the one side face extends in a direction of the combined vector, and the slide die moves along the inner wall. wherein the stationary die comprises a main die and a slide die that moves relative to the main die, the slide die partially faces the cavity and moves in a predetermined direction different from a die clamping and die opening direction; a face (32,33) of the slide die that faces the cavity comprises a plurality of faces (32,33) extending in a plurality of directions that are not mutually in parallel, wherein the plurality of faces (32,33) of the slide die include a face orthogonal to the die clamping and die opening direction and another face, wherein the main die comprises an accommodation space that accommodates the slide die partially or entirely; the accommodation space is molded so as to allow the slide die to move in the predetermined direction; the slide die is moved by an actuator so as to form a cavity for the foam layer in accordance with growth of the foam layer; the predetermined direction of the slide die is orthogonal to a combined vector determined by combining respective linear vectors, each respective linear vector being orthogonal to a respective one of the plurality of faces (32,33) extending in a plurality of directions making up the face of the slide die that faces the cavity and determined based on an area ratio of the respective face, one side face of the slide die is pushed out by an actuator, an inner wall of the movable die opposed to another side face of the slide die on the opposite side of the one side face extends in a direction of the combined vector, and the slide die moves along the inner wall.