This method of manufacturing a lid made of a transparent resin comprises a step of introducing a resin into a cavity for molding a protrusion continuous with a cavity for molding a lid in a die; a step of forming a molded body including a lid and a protrusion continuous with the lid by solidifying the resin in the cavity for molding a lid and the cavity for molding a protrusion, respectively; a step of separating the molded body from the die by ejecting an ejector pin to the protrusion; and a step of separating the protrusion from the lid.