To provide a seat with a seating sensor which can detect the passenger's various weight, large and small, by simple constitution.

An upwardly oriented recess 2 is provided to the undersurface of the bottom face of the under-hip of a pad 1, and a soft element 3 is fitted in the recess 2. Then a first protrusion 3a of relatively small height and a second protrusion 3b of relatively large height are provided on the top surface of the soft element 3. A first seating sensor 4 is provided on the top surface of the first protrusion 3a, and the second seating sensor 5 is provided on the top surface of the second protrusion 3b. The threshold values of the sensors 4, 5 are the same.