A seat cushion of a vehicle seat comprising a mounting structure for mounting a load detection device to a cushion member of the seat cushion, the seat cushion comprising: the load detection device comprises a plurality of detecting portions for detecting load information and one or more connecting portions for connecting the detecting portions; the cushion member includes a plurality of detecting portion disposing portions for disposing the detecting portions, respectively, one or more connecting portion disposing portions for disposing the one or more connecting portions, respectively, and a recessed portion formed in only one connection portion disposing portion (13e3) of the connecting portion disposing portions, both sides of the recessed portion being arranged with the detecting portion disposing portions; the recessed portion is a groove formed as a decorative groove of the seat cushion or a suspending groove for suspending a surface skin member of the seat cushion; the load detection device is mounted on the cushion member in such a manner that the respective detecting portions are disposed on the respective detecting portion disposing portions, the one or more connecting portions are disposed on the connecting portion disposing portions, and only one connecting portion of the connecting portions is disposed in said only one connection portion disposing portion (13e3) of the connecting portion disposing portions, said only one connecting portion of the connecting portions crossing over the recessed portion and being disposed in the recessed portion, so that a pitch distance between the detecting portions connected by said only one connecting portion of the connecting portions can be adjusted by utilizing the recessed portion; a double-sided adhesive tape is stuck to the back surface of all the connecting portions and the double-sided adhesive tape is not stuck to the back surface of the detecting portions, and all the connecting portions are adhered and fixed on the upper surface of the cushion member by means of the double-sided adhesive tape. the load detection device comprises a plurality of detecting portions for detecting load information and one or more connecting portions for connecting the detecting portions; the cushion member includes a plurality of detecting portion disposing portions for disposing the detecting portions, respectively, one or more connecting portion disposing portions for disposing the one or more connecting portions, respectively, and a recessed portion formed in only one connection portion disposing portion (13e3) of the connecting portion disposing portions, both sides of the recessed portion being arranged with the detecting portion disposing portions; the recessed portion is a groove formed as a decorative groove of the seat cushion or a suspending groove for suspending a surface skin member of the seat cushion; the load detection device is mounted on the cushion member in such a manner that the respective detecting portions are disposed on the respective detecting portion disposing portions, the one or more connecting portions are disposed on the connecting portion disposing portions, and only one connecting portion of the connecting portions is disposed in said only one connection portion disposing portion (13e3) of the connecting portion disposing portions, said only one connecting portion of the connecting portions crossing over the recessed portion and being disposed in the recessed portion, so that a pitch distance between the detecting portions connected by said only one connecting portion of the connecting portions can be adjusted by utilizing the recessed portion; a double-sided adhesive tape is stuck to the back surface of all the connecting portions and the double-sided adhesive tape is not stuck to the back surface of the detecting portions, and all the connecting portions are adhered and fixed on the upper surface of the cushion member by means of the double-sided adhesive tape.