To provide an fitting structure of a switch module for a sheet in which the assembling performance of an operation switch can be enhanced.

A moving connector 16 which is connected to one end of a sheet harness W whose other end is connected to a sheet unit is fixed to a sheet cushion frame 11 so as to be turnable. The moving connector 16 is mounted on a case 14 so as to conduct minute displacement, and the case 14 is fixed to one end of the fitting frame 13. The other end of the fitting frame 13 is supported by an angle member 12 so as to be turnable around a spindle 21. The angle member 12 is equipped with a stopper 12a, a positioning recessed portion 12b, and a fixing recessed portion 12c. A switch module 19 is fixed to an opening portion 17a. The switch module 19 is equipped with operation switches 19a, 19b, and an connection connector 22 mounted on a circuit board 23 is disposed.