A method of manufacturing a steering wheel, in which a coating layer is molded of a synthetic resin, by using a molding die unit, on at least the annular portion of a steering wheel core including a boss. The annular portion is located around the boss and has a groove extending in the circumferential direction thereof. Spokes couple the boss and the annular portion to each other. The method includes a die opening step in which an upper molding die and a lower molding die, which have a gate formed at the separation surfaces of the dies and communicating with the molding cavity of the die unit, are opened from each other. The second step is a core setting step in which the core is set in the cavity so that the outermost part of the groove of the annular portion having walls defining the groove between them is located as the top of the groove, one of the walls, which faces the gate and has a notched part notched to be smaller in height than the other of the walls, faces the gate at the notched part, and the top of the notched part is located below the separation surfaces. Third, a coating layer molding step is carried out in which the dies are closed on each other and the resin is injected into the cavity through the gate so that the coating layer is molded of the resin on the core. Last and a steering wheel takeout step in which the dies are opened from each other and the wheel is taken out from the dies is accomplished.