A seat sliding device for a vehicle includes a sliding load adjusting mechanism. The sliding load adjusting mechanism includes a support member, which is fixed to a first rail that is one of a lower rail and an upper rail, and a pressing member, which is movably supported by the support member. The pressing member changes a frictional force that is generated between the pressing member and a second rail, which is the other one of the lower rail and the upper rail, in accordance with a pressing force applied to the second rail. The pressing force changes in accordance with the position of the pressing member in relation to the support member. As the upper rail moves in a first direction, the pressing member moves toward a side on which the pressing force is reduced.