A method for manufacturing interdental cleaning devices, each including: a base portion that is formed by molding a synthetic resin material and includes a handle portion and a core portion provided at a front end of the handle portion and having a slender shaft shape; and a soft portion that is formed on the base portion by molding an elastomeric material, and includes a cleaning soft portion substantially covering at least part of the core portion, a non-slip portion substantially covering at least part of the handle portion, and connecting portions also covering at least part of the handle portion, extending from two sites of the non-slip portion, and being connected to the cleaning soft portion, the method comprising: providing molds (40, 41) forming a plurality of soft portion molding spaces in parallel at mating surfaces of the molds (40, 41) to form the soft portions, wherein each soft portion molding space is provided in such a manner that the opening of a gate is located at the mating surfaces of the molds (40, 41) at a position substantially equally distant from positions of two communicating openings of a non-slip molding space for molding the non-slip portion that communicate with connecting portion molding spaces for molding the connecting portions; and wherein a common supply channel is formed in one of the molds to extend to a substantially central position between adjacent non-slip portion molding spaces, and individual supply channels are branched from the substantially central position to the opposed positions of the non-slip portion molding spaces and formed to reach the openings of the gates, and charging the elastomeric material into each of the soft portion molding spaces to fill the soft portion molding space through the common supply channel, the individual supply channel, and the gate. a base portion that is formed by molding a synthetic resin material and includes a handle portion and a core portion provided at a front end of the handle portion and having a slender shaft shape; and a soft portion that is formed on the base portion by molding an elastomeric material, and includes a cleaning soft portion substantially covering at least part of the core portion, a non-slip portion substantially covering at least part of the handle portion, and connecting portions also covering at least part of the handle portion, extending from two sites of the non-slip portion, and being connected to the cleaning soft portion, the method comprising: providing molds (40, 41) forming a plurality of soft portion molding spaces in parallel at mating surfaces of the molds (40, 41) to form the soft portions, wherein each soft portion molding space is provided in such a manner that the opening of a gate is located at the mating surfaces of the molds (40, 41) at a position substantially equally distant from positions of two communicating openings of a non-slip molding space for molding the non-slip portion that communicate with connecting portion molding spaces for molding the connecting portions; and wherein a common supply channel is formed in one of the molds to extend to a substantially central position between adjacent non-slip portion molding spaces, and individual supply channels are branched from the substantially central position to the opposed positions of the non-slip portion molding spaces and formed to reach the openings of the gates, and charging the elastomeric material into each of the soft portion molding spaces to fill the soft portion molding space through the common supply channel, the individual supply channel, and the gate. providing molds (40, 41) forming a plurality of soft portion molding spaces in parallel at mating surfaces of the molds (40, 41) to form the soft portions, wherein each soft portion molding space is provided in such a manner that the opening of a gate is located at the mating surfaces of the molds (40, 41) at a position substantially equally distant from positions of two communicating openings of a non-slip molding space for molding the non-slip portion that communicate with connecting portion molding spaces for molding the connecting portions; and wherein a common supply channel is formed in one of the molds to extend to a substantially central position between adjacent non-slip portion molding spaces, and individual supply channels are branched from the substantially central position to the opposed positions of the non-slip portion molding spaces and formed to reach the openings of the gates, and charging the elastomeric material into each of the soft portion molding spaces to fill the soft portion molding space through the common supply channel, the individual supply channel, and the gate.