A folding vehicle seat is adapted to be stored on a first portion of a vehicle body floor and retained on the first portion by a retaining belt arrangement which includes a belt attached at its lower end to a vertical wall extending upward from the floor and a hook attached to an upper end of the belt. The upper end is inserted through a ring attached to the wall. The seat includes a seat cushion pivotally supported on a second portion of the floor and a seat back pivotally supported by the cushion, the cushion and back being adapted to be put together as a single body which is adapted to be pivoted from the second portion toward the first portion and has an engagement mechanism with which the hook is adapted to be engaged at the time when the body is stored on the first portion.