Patent attributes
Provided is a slide device that can prevent rattling of a seat with a simple structure. A slide device includes a lock mechanism for fixing an upper rail to a lower rail. The lock mechanism includes a shaft attached to the upper rail, a lock tooth swingably supported by the shaft, and a wave washer that presses the lock tooth in an axial direction of the shaft. An outer circumferential face of the shaft has an outer tapered face slanted so that the shaft becomes thinner along a direction from a proximal end portion toward a distal end portion. An inner circumferential face of the shaft hole of the lock tooth has an inner tapered face having a slant angle that allows face-to-face contact with the outer tapered face. The wave washer presses the lock tooth in a direction in which the inner tapered face is pressed against the outer tapered face to make face-to-face contact.