A seat track apparatus is provided including a first rail disposed on one of a floor side and a seat side, a second rail disposed on the other one of the floor side and the seat side and engaged with the first rail so as to be relatively movable, and a lock mechanism (71) configured to restrict the relative movement of the first rail and the second rail, the lock mechanism (71) includes a lock groove (73) formed on a lower rail (51) and a lock member (75) disposed on an upper rail (61), and the lock member (75) includes a rotation restricting portion (75c) which is brought into press-contact with the upper rail (61) from one side (upper side) to the other side (lower side) with respect to a straight line (L) passing through both end portions thereof.