To provide a locking mechanism in a seat track sliding device for a vehicle which can not only surely maintain a locked state by allowing a positional slippage between a pair of lock levers, but also facilitate the assembling work between the lock levers and an operating handle. Under the locked state R of the lock levers 12, the lock levers 12 can relatively turn to an operation turning central axis 15a about the shift allowable turning central axis 26a which is set at an engaging part 26 between the lock levers 12 and a lower rail 3 as the pivot. This shift allowable turning central axis 26a is a common central axis owned by an arch-shape relative moving track of sliding pairs 16 and 20 between the lock levers 12 and an upper rail 5. The operation turning central axis 15a is a turning central axis at a revolute pair 15 between the lock levers 12 and the upper rail 5. Also, the operation turning central axis is a common virtual central axis owned by the arc-shape relative moving track of respective sliding pair between the lock levers and the upper rail. (C)2005,JPO&NCIPI . |