PURPOSE: To adjust the height of a form according to that of a wall to be constructed by using a pair of concrete forms one of which consists of an upper form and a lower form and can be vertically freely moved.

CONSTITUTION: Rails D are placed in parallel with a wall to be constructed on a foundation C, and forms A and B are put on wheels 14. The form B consists of a lower form B1 and an upper form B2 which are vertically moved for regulation alternately by means of a jack 8. The verticality of the form B is adjusted by the jack 37 of a regulating lever 36. Both the forms A and B are set at a given interval by means of the jack 23 and then concrete is placed. When the form is removed, the upper part of the form A is opened outwards by the jack 23, the upper part of the form B is opened outwards by the jack 37, the forms A and B are separated from the placed concrete by a jack 20, and the forms A and B are moved on the rails.