Provided according to the present invention is a solenoid with a built-in permanent magnet, with which it is possible to suppress an increase in the amount of magnetic flux that passes through the chuck part, even when the magnetic flux generated by a coil is greater than the magnetic flux of the magnet, and to reliably reduce attraction force. In this solenoid (10), a permanent magnet (13) and a coil (16) are both built into a cylindrical case (11) having an opening part (12); the permanent magnet and the coil are both separated and arranged inside the case; a ring member (14) is arranged adjacent to the permanent magnet; a movable iron core (19) is inserted inside the coil; and between the movable iron core and the coil, a metal coil cover (17) is provided so as to cover the coil. The distance d between the case inner wall and the ring member can also be in the range of 0.1-0.3 mm.