A solenoid includes a molded coil having a hole at the center of a coil of a plurality of turns, a solenoid body having a case covering the outer perimeter of the molded coil, a movable plunger inserted in the hole, and a magnetic attraction portion disposed in a direction in which the plunger is moved and attracted by magnetic force produced by the coil, an annular plate adjacent to the coil of the molded coil opposite to the solenoid body, and a sleeve facing the magnetic attraction portion via an air gap and supporting one end of a rod connected to the plunger, in which a magnetic circuit L is formed through the magnetic attraction portion, the case, the sleeve, and the plunger, and back to the magnetic attraction portion, and the plunger has at least one outer edge extension formed by an outer edge portion extended axially.