A bobbin unit includes a base portion and a coil winding portion on which a conductor is wound. A hole is formed in a central part of the base portion to allow an armature to pass through. Coil side terminals to which ends of the conductor are fixed and signal input terminals to which an external signal is entered are provided at opposite ends of the base portion with the hole located in between. The coil side terminals are electrically connected to their corresponding signal input terminals inside the base portion. A coil is formed on the coil winding portion by winding the conductor. The ends of the conductor are wound around the respective coil side terminals and fixed thereto by arc welding. Since the conductor is electrically connected to the signal input terminals when the ends of the conductor are fixed to the coil side terminals, connection of the ends of the conductor constituting the coil to the signal input terminals is made easy. Furthermore, the length of lead wire portions between the coil and the coil side terminals is shortened, making it possible to prevent breakage of the conductor between the coil and the coil side terminals.