To provide a plate coupling device capable of coupling plates by easily driving a screw into a hole in a screw receptacle metal piece.

The plate coupling device includes the screw receptacle A made of a synthetic resin, at least two plate members B and C to be coupled together at a right angle, and the long stretching coupling screw D. Either plate member B is furnished at its surface with a receptacle inserting hole 7 extending across the thickness of the plate member B, and a communication hole 8 having communication with the receptacle inserting hole 7 from the side end face 5 of the plate member B is provided, while a through-hole 9 having communication with the hole 8 penetrates the other plate member C from the outer surface of the plate member C. The screw receptacle A has a columnar shaft part 1 which is made of a synthetic resin and furnished with a screw inserting hole 2 penetrating in the direction perpendicularly crossing the axis of the shaft part 1. A metal nut member together with the shaft part 1 is insert-molded in the middle position of the hole 2. The threaded hole of the nut member is formed as to make engagement with the coupling screw D, and a long groove 10 extending along the axis of the screw inserting hole 2 is formed on the upper surface of the shaft part 1.