To realize the easy pulling-out of a large number of rod-like mold members for forming smaller diametral through holes even after the setting of a concrete.

In this device, a molding form, on the inner surface of the main body 10 of which for forming the external shape of a concrete plate a large number of rod-like mold members 13 for molding the perforated portion of the concrete plate to be molded are projected, is employed so as to lay and fill a concrete in the molding form under the condition that one or several times of the rotating action about the axis center of the rod-like mold member 13 and/or of the shifting action toward its axis center are given to each rod-like mold member 13 during the period between the starting and finish of the setting of the cement of the concrete. As a result, the adhesion between the rod-like mold member 13 and the concrete is reduced before the setting of the concrete.