A heat conductive plate structure includes a base metal plate having a seating portion; a coupling layer disposed above the base metal plate around the seating portion; an electric conduction layer disposed above the coupling layer around the seating portion to define a clearance therebetween; a coupling film disposed above the electric conduction layer and the seating portion to define an inner clearance in communication with the clearance of the electric conduction layer and an outer clearance surrounding the inner clearance; a non-weldable material for inserting into the inner clearance and the outer clearance in the coupling film; a heat conduction member disposed on a central portion of the coupling film; an electric conduction member disposed above the coupling film to surround the heat conduction member from an exterior thereof; and a high power element mounted above so as to be in direct contact with the heat conduction member and the electric conduction member simultaneously.