A process for forming a concrete wall having a projecting portion such as those formed at a door, windows or the like, including installing two spaced apart opposite form boards which confine a cavity for receiving concrete, one of which has a groove for forming the projecting portion, lining the wall segments with a cushion member which is made of a flexible and compressible material, pouring concrete into the cavity, and moving simultaneously the form board from the formed concrete in a direction similar to the direction of the projecting portion utilizing a hydraulic drive mechanism.