The present invention provides a resin leakage prevention member 401 for use in a molding die 1000, wherein the molding die 1000 includes a lower die 200 and an upper die 100, the lower die 200 has a side member 201 and a bottom member 202, a space surrounded by the side member 201 and the bottom member 202 forms a cavity 204, the cavity 204 is configured to accommodate a resin material 20a, the side member 201 is configured to move relatively vertical to the bottom member 202, and the resin leakage prevention member 401 is disposed on a peripheral portion of an upper surface of the bottom member 202 and along an inner peripheral surface of the side member 201, thereby sealing a gap between the side member 201 and the bottom member 202 and preventing a resin from leaking from the cavity 204 into the gap.