Abstract: A vehicular rear seat unit (1) includes a bench seat (2) including a seat cushion (7) with three seat sections (4, 5, 6) arranged side by side, the seat cushion having a pair of frame members (23, 30, 24, 31) provided at positions corresponding to both side portions of the middle seat section (4); seat belt anchors (A, B, C, D) for the seat sections (4, 5, 6), the seat belt anchors (A, B, C, D) being attached to the respective frame members (23, 30, 24, 31); and a seat slide device (3) including a pair of movable rails (29) to which the respective frame members (23, 30, 24, 31) are individually fixed, and a pair of fixed rails (28) which slidably support the respective movable rails (29), the fixed rails (28) being individually fixed to a vehicle body floor.