A front seat 31 is foldable such that a seat back 33 is frontwardly collapsed and placed on a seat cushion 32, a rear seat 39 is foldable such that a seat back 41 is frontwardly collapsed and placed on a seat cushion 40, and a trunk floor 53 extending from a front pillar 12 to a rear pillar 14 is formable by laying a trunk board 49 across a gap formed between a rear face of the seat back 33 of the front seat 31 and a rear face of the seat back 41 of the rear seat 39 with the front seat 31 and the rear seat 39 in a folded state.