The bus bar wiring plate body (20) for an electric coupling box according to the present invention is arranged in a manner that bus bar members (23, 24) are wired between pre-hardening epoxy resin plates (21, 22) and these pre-hardening epoxy resin plates are subjected to the heat pressing process to thereby integrate the pre-hardening epoxy resin plates (21, 22) and the bus bar members (23, 24) in a laminated state. When hardened epoxy resin plates (25, 26) are disposed at the outsides of the pre-hardening epoxy resin plates (21, 22) as shown by phantom lines, respectively, the strength of the bus bar wiring plate body (20) can be improved. Thus, since the bus bar members (23, 24) are sealed in an insulated state, leak current can be reduced surely. Further, the thickness of the bus bar wiring plate body (20) can be reduced to a large extent, so that the electric coupling box can be miniaturized and lightweighted.