In addition, though not shown, various electric parts which form the circuit of the electronic apparatus are mounted on the oppositesurfaces of sub-printed board 3.The state after connectors 23, 33 of main printed board 2 and sub-printed board 3 have been mated with each other are described in detail with reference to FIGS. 4, 5 and 6A, 6B, 6C. FIG. 4 is a perspective view of an appearance of the