The present invention includes a valve seat and a valve body that cooperatively open/close a fuel passage, a movable element having the valve body provided at one end part thereof and a movable iron core 27a provided at the other end part thereof, a fixed iron core 25 which faces the movable iron core 27a and which attracts the movable iron core 27a by applying a magnetic attraction force thereto, and a cylindrical member that includes thereinside the fixed iron core 25 and the movable iron core 27a. The fixed iron core 25 includes a reduced-diameter part 25m on an outer circumferential surface at the side facing the movable iron core 27a, and the movable iron core 27a includes a reduced-diameter part 27am on an outer circumferential surface at the side facing the fixed iron core 25.