PURPOSE: To increase adhesiveness of end surface by forming the end part of a plastic mold on an end surface crossed at right angle to a main surface and, when the frame is assembled, butting the adjacent end parts with each other with the end surfaces surface-contacted with each other.

CONSTITUTION: A concrete mold 11 is formed by a integral forming method using a metal mold. In this case, a rise wall 13 is tapered except for an end surface 15 as a result of the pattern draft provided on the metal mold. Also the end surface 15 is positioned at right angle to a main surface 14, and dimensions in vertical direction are made longer as far as practicable within the range where the metal mold can be drawn. Then, when multiple molds 11 are connected by a clip 6, adjacent end parts 12 are made in contact closely with each other by surface contact of the end surface 15. Thus deposited concrete is prevented from coming out of the end surface.