PROBLEM TO BE SOLVED: To improve reliability of information 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, which is longitudinally extended on the horizontal outside with respect to the mounting surface part 1, is formed as a projection having a tip 5b directed toward a seat frame 11.SELECTED DRAWING: Figure 2