The load-detecting device 1 includes a base 2 engaged with a pair of S springs 100, and a load detection sensor unit SU that is mounted on the base 2 and includes a first electrode 52 and a second electrode 62 facing each other and being brought into contact with each other by pressing force of the seat cushion SC when a load is detected, The upper surface 47S of the load detection sensor unit SU that is pressed by the seat cushion SC when a load is detected is located at the same height as or higher than the upper ends 101 of the respective S springs 100, with which the base 2 is engaged, and the contact surface between the first electrode 52 and the second electrode 62 is located lower than the upper ends 101 of the respective S springs 100, with which the base 2 is engaged.