A method for manufacturing a motor, the motor comprising: a stator; a rotor disposed inside the stator; and a shaft coupled to the rotor, wherein the rotor includes a rotor core disposed outside the shaft, a magnet disposed outside the rotor core, and a molding portion which molds the rotor core and the magnet, and the molding portion includes an upper part disposed on an upper surface of the magnet, a lower part disposed on a lower surface of the magnet, a lateral part disposed on a side surface of the magnet, and a protrusion part which protrudes from the lateral part in an axial direction of the shaft, wherein the protrusion part is disposed at the portion where the lower part and the lateral part are connected, wherein the method comprises: performing an injection molding to surround the rotor core and the magnet by the molding portion, in order to mold the rotor core and the magnet, such that the molding portion includes said upper part, said lower part, said lateral part, and said protrusion part, wherein said protrusion part is disposed at the portion where said lower part and said lateral part are connected, and the injection molding comprises: injecting a flow of molding through an injection molding gate which is connected to said upper part, flowing the molding from said upper part to said lateral part, and flowing the molding from said lateral part to said lower part via said protrusion part, wherein said protrusion part is a region unrelated to a function of the molding portion, such that said protrusion part leads overflow to guide air traps or weld lines (E, D) to move to said protrusion part during the injection molding, and wherein said lower part, said upper part, said protrusion part, and said lateral part of the molding portion are formed through the injection molding as a single part. a stator; a rotor disposed inside the stator; and a shaft coupled to the rotor, wherein the rotor includes a rotor core disposed outside the shaft, a magnet disposed outside the rotor core, and a molding portion which molds the rotor core and the magnet, and the molding portion includes an upper part disposed on an upper surface of the magnet, a lower part disposed on a lower surface of the magnet, a lateral part disposed on a side surface of the magnet, and a protrusion part which protrudes from the lateral part in an axial direction of the shaft, wherein the protrusion part is disposed at the portion where the lower part and the lateral part are connected, wherein the method comprises: performing an injection molding to surround the rotor core and the magnet by the molding portion, in order to mold the rotor core and the magnet, such that the molding portion includes said upper part, said lower part, said lateral part, and said protrusion part, wherein said protrusion part is disposed at the portion where said lower part and said lateral part are connected, and the injection molding comprises: injecting a flow of molding through an injection molding gate which is connected to said upper part, flowing the molding from said upper part to said lateral part, and flowing the molding from said lateral part to said lower part via said protrusion part, wherein said protrusion part is a region unrelated to a function of the molding portion, such that said protrusion part leads overflow to guide air traps or weld lines (E, D) to move to said protrusion part during the injection molding, and wherein said lower part, said upper part, said protrusion part, and said lateral part of the molding portion are formed through the injection molding as a single part. performing an injection molding to surround the rotor core and the magnet by the molding portion, in order to mold the rotor core and the magnet, such that the molding portion includes said upper part, said lower part, said lateral part, and said protrusion part, wherein said protrusion part is disposed at the portion where said lower part and said lateral part are connected, and the injection molding comprises: injecting a flow of molding through an injection molding gate which is connected to said upper part, flowing the molding from said upper part to said lateral part, and flowing the molding from said lateral part to said lower part via said protrusion part, wherein said protrusion part is a region unrelated to a function of the molding portion, such that said protrusion part leads overflow to guide air traps or weld lines (E, D) to move to said protrusion part during the injection molding, and wherein said lower part, said upper part, said protrusion part, and said lateral part of the molding portion are formed through the injection molding as a single part. injecting a flow of molding through an injection molding gate which is connected to said upper part, flowing the molding from said upper part to said lateral part, and flowing the molding from said lateral part to said lower part via said protrusion part, wherein said protrusion part is a region unrelated to a function of the molding portion, such that said protrusion part leads overflow to guide air traps or weld lines (E, D) to move to said protrusion part during the injection molding, and wherein said lower part, said upper part, said protrusion part, and said lateral part of the molding portion are formed through the injection molding as a single part.