PURPOSE: To improve the soundproofness and heat-insulating properties of a composite window glass by attaching a board to be attached consisting of a resin board on one surface of a plate glass and forming a plurality of air layers between one surface of the plate glass and the board to be attached.

CONSTITUTION: Boards to be attached 3, 3 composed of a resin board are attached on one surfaces of plate glasses 2, 2 constituting composite window glasses 1, 1. A plurality of space-holding structure in constant height are protruded to surfaces oppositely faced to the surfaces of the plate glasses 2 of the boards to be attached 3, and working faces against the plate glasses 2 are bonded with the plate glasses 2 by adhesives and an adhesive tape. Accordingly, a plurality of air layers 4... are formed among the boards to be attached 3 and one surfaces of the plate glasses 2, thus displaying soundproofness and heat-insulating properties. The same effect is also displayed even as a hollow sheet-shaped resin board, in which the boards to be attached are formed in a corrugated structure and a honeycomb structure.