To save the labour for a molding work, increase its efficiency, ensure its safety or the like by a method wherein the mold-closing and mold-opening operations are automated by connecting a rising and falling side frame and an advancing and retreating side frame respectively with a rising and falling device and with an advancing and retreating device.

In a concrete form, the mold closing and mold opening of one side frame is performed through a rising and a falling actions by engaging a bearing provided at the lower part of one side frame with a horizontal pivot provided at one side of a surface plate, while the mold closing and mold opening of the other side frame is performed through an advancing and a retreating actions by engaging a running body provided at the lower part of the other side frame with a horizontal guide provided at the other side of the surface plate, a rising and falling device 14, which raises the one side frame to its mold closing position and falls it to its mold opening position, is connected with the one side frame 2 while an advancing and retreating device 24, which advances the running body 10 of the other side frame 3 to its mold closing position and retreats it to its mold opening position, is connected with the other side frame 3.