A LSI package encompasses: an interposer having board-connecting joints, which facilitate connection with a printed wiring board, and module-connecting terminals, part of the module-connecting terminals are assigned as interposer-site monitoring terminals; a signal processing LSI mounted on the interposer; and an I/F module having a plurality of interposer-connecting terminals, which are arranged to correspond to arrangement of the module-connecting terminals, and a transmission line to establish an external interconnection of signal, which is transmitted from the signal processing LSI, part of the interposer-connecting terminals are assigned as module-site monitoring terminals. The interposer-site and module-site monitoring terminals are configured to flow a monitoring current to confirm electric contact between the signal processing LSI and the I/F module.