The present invention provides a semiconductor device which can realize the mounting of a plurality of chips at a high-speed, with high packaging density and at a low cost. In mounting a memory device chip 103 and an ASIC 104 on a wiring chip 102, connection pads 110, 116 are respectively formed along one opposing sides of the memory device chip 103 and the ASIC 104 on the wiring chip 102, the arrangement positions of the respective connection pads 110, 116 define the shortest distance assumes the shortest distance therebetween and, at the same time wiring lines which are formed on the wiring chip 102 are also shortened. Accordingly, it is possible to mount the memory device chip 103 and the ASIC 104 on the wiring chip 102 with high packaging density and, at the same time, since the wiring distance can be shortened, the high speed operation can be realized.