PROBLEM TO BE SOLVED: To suppress a decrease in detection accuracy of a vital sensor mounted on a seat pan of a vehicle seat.SOLUTION: A seat pan 18 comprises a mounting surface part 1 and a deformation part 2. A sensor 30 for detecting occupant's biological information is mounted on the mounting surface part 1. The deformation part 2 is longitudinally extended on the horizontal outside with respect to the mounting surface part 1. Additionally, the deformation part 2 has a V-shaped cross-section, the tip 5b of which is directed upward or downward.SELECTED DRAWING: Figure 2