PURPOSE: To enable a collapsible board to have good portability and to be solid during use by collapsibly coupling square board members with a hinge part, expanding It during use, and making both the board members into one by permitting a fastening metal piece to slide to the hinge part.

CONSTITUTION: Square plates 1, 1 are connected to be collapsibly superimposed each other via a hinge part 2. The plate members 1, 1 are formed of a rigid plastic material or the like. A substantially brought-down U-shaped fastening metal piece 3 consisting of an elastic rigid material such as a thin rigid plastic is slidably mounted on one side periphery being perpendicular to the hinge parts of the plate members. Further, on the inner surfaces of the plate members, pockets 4 are made in a manner capable of housing cards, papers and the like. Grips 5, 5 are provided on both end parts of the plate members 1, 1. During the period of carrying it, the fastening metal piece 3 is positioned out of the hinge part 2 for grasping the grips 5, 5 in a collapsed state. During use, the plate members are opened, and the fastening metal piece 3 is moved from the hinge part 2 to fasten the plate members into a state of one board.