PURPOSE: To raise the productional efficiency of concrete blocks by a method in which projected weirs of the same height as the thickness of the block are provided over the full width on the outside near the straight both edges of a V-shaped formwork, the formworks are stacked plurally in a row, and then cement concrete is placed into the formworks.

CONSTITUTION: A formwork A is vertically set on the flat face in a support frame 4 by turning its V-shaped edges vertically, the formworks are plurally stacked in a row by arranging their bent directions and by contacting their projected weirs 2 and 2a with the adjacent formworks and clamped with a screw 4, and then ready mixed concrete is placed into the spaces B of the formworks.