PURPOSE: To lower the number of defective spectacle frames remarkably so as to obtain a spectacle frame inexpensively, by using as a core a ring for forming a lens groove, which ring is obtained by molding a flexible resin material whose melting point is higher than that of a synthetic resin for the intended spectacle frame.

CONSTITUTION: In case when a spectacle frame of a synthetic resin is molded using a mold, use is made of as a core a ring for forming a lens groove, which ring is obtained by molding a flexible resin material whose melting point is higher than that of a synthetic resin for the intended spectacle frame.

EFFECT: Compared with the conventional metal core, the present core can be easily produced and is inexpensive. As the present core is obtained by molding a flexible resin, it can be clamped firmly in a mold without forming any gap therebetween, burr would hardly be formed and therefore the number of defective items can be decreased remarkably.