PURPOSE: To mount circuit parts on a printed wiring board at a high packaging density so as to reduce the size and increase the signal transmitting speed of the board by constituting shielding plates provided with leg pieces to be passed through through-holes of the board to have a shielding structure to be mounted on the mounting surface side of the board.

CONSTITUTION: Shielding plates 20 are mounted on a printed wiring board 1 in a state where main plate members 21 of the plates 20 are mounted on the mounting surface side of the board 1, with leg pieces 25 of the plates 20 being passed through slit-type through holes 2 formed in the board 1 along partitioning lines, and upper-side edges 22 of the plates 20 are firmly adhered to an upper cover 10. Front end sections of the leg pieces 25 are put in and firmly adhered to slits 16 formed in a lower cover 15. Thus circuit parts which are mounted on the board 1 and may cause electro-magnetic interference with each other are completely partitioned and shielded from each other by the main plate members 21. Therefore, even when circuit parts are mounted on one printed wiring board at a high packaging density, the possibility of the interference between the parts can be eliminated. Moreover, the printed circuit board thus manufactured can be reduced in line length and improved in signal transmitting speed as compared with the circuit board using connectors, etc., for connection.