Abstract: A method of removing voids from a molded product is disclosed, in which a main mold, is connected with an auxiliary mold, and molten material in the auxiliary mold moves toward the main mold by adjusting a cooling time between the main mold and the auxiliary mold, thereby preventing voids from occurring in the molded product having a large thickness, preventing sink marks from occurring. The method includes the steps of: preparing a main mold and an auxiliary mold connected with the main mold; introducing molten resin into the auxiliary mold and the main mold; and retarding cooling of the auxiliary mold such that negative pressure in the auxiliary mold is different from that in the main mold due to a cooling time difference and a temperature difference. The molten resin in the auxiliary mold moves toward the main mold, and then is filled in the main mold during cooling.