A magnetic recording/reproducing device of the present invention includes: a loading motor for driving a mechanism section; a holder section for maintaining the loading motor at a prescribed position; a worm gear rotatable along with a rotation shaft of the loading motor; and a worm gear bearing member integrally formed with the holder section, the worm gear bearing member being in contact with a tip of the worm gear, the worm gear bearing member includes a first deflection portion deflectable along a thrust direction along a rotation axis of the worm gear and a second deflection portion deflectable along a radial direction to the rotation axis of the worm gear, and force is generated at the tip of the worm gear along the thrust direction thereof by simultaneously deflecting the first and second deflection portions so as to define a position of the worm gear along the thrust direction thereof.