A semiconductor device mounting socket is disclosed that is fixed to a motherboard and is used for mounting a surface mounted semiconductor device on the motherboard. The semiconductor device mounting socket includes a bracket that is fixed to the motherboard and a pad pitch converting member that is arranged within the bracket. The pad pitch converting member includes an upper face on which semiconductor device side pads are arranged at a first pitch corresponding to the pitch of pads of the surface mounted semiconductor device, and a lower face on which motherboard side pads that are electrically connected to the semiconductor device side pads are arranged at a second pitch that is different from the first pitch. The surface mounted semiconductor device is arranged above the pad pitch converting member within the bracket.