To miniaturize a recess in a structure in which a seat back is forwardly folded on a seat cushion, and a seat is backwardly turned, and stored in the recess of a vehicle floor.

In a third row seat 3 of a vehicle V, a seat back 32 is forwardly folded on a seat cushion 31, and a head rest 33 is backwardly turnable with respect to the seat back 32. The seat cushion 31 is supported by a floor 4 in a backwardly turnable manner. A recess 41 is formed behind the third row seat 3 on the floor 4 of the vehicle V, and the third row seat 3 is stored in the recess 41 when the third row seat 3 is turned backwardly while the seat back 32 of the third row seat 3 is forwardly folded, and the head rest 33 is turned backwardly. An outer edge of a turning locus of the seat cushion 31 is substantially matched with an outer edge of a turning locus of the seat back 32, and a rear end 4R of the recess 41 is located on the turning locus.