A load sensing device, which includes a load detecting device adapted to a seat and outputting a load signal in response to a strain generated at the load detecting device and which detects a load applied to the seat on the basis of the load signal, includes a determining device determining whether the seat is in an occupied state or in a vacant state based on a magnitude relationship between the load and a threshold value, a collision detecting device detecting a shock generated when a vehicle collides, an alarming device alarming that the shock is detected, and a memorizing device storing a diagnosis information indicating whether or not a zero-point adjustment of the load detecting device needs to be executed in response to a determination result of a state of the seat in the case where the shock is detected by the load detecting member.