By stacking and mounting a second substrate 20 having the same structure as that of a first substrate 10 on the first substrate upon rotating the second substrate by 180 degrees and sliding the second substrate, an antenna 11 and an antenna 22 overlap each other and an antenna 12 and an antenna 21 overlap each other and communications in each of these combinations are enabled, and a space for wire bondings 16 is secured. Accordingly, communications between the substrates are made via the antennas, and further, a space for wire bondings is secured on each substrate, wireless communications are carried out between substrates which have the same basic structure and are stacked and mounted, and power can be supplied via the wire bondings.