A seat for a vehicle has an upper panel provided integrally with a seat back which can be tilted forward and rearward by operating an operation lever for reclining use. At a first operation position of an operation lever for walk-inuse, the operation lever for walk-in use is interlocked with the operation lever for reclining use through a linking arm to tilt the upper panel urged by a spring forward. A projected piece mounted on the upper panel contacts a slide-unlocking lever and operates the slide-unlocking lever to rotate in an unlocking direction. Thereby slide locking of the seat for thevehicle is released. At a second operation position of the operation lever for walk-in use, the slide-unlocking lever is operated directly by a linking plate. Thereby the slide locking of the seat for the vehicle is released.