To provide a form capable of simultaneously placing concrete to a bottom bed and a rising section in the construction of a foundation.

This form 1, 2 comprises a form fixture 10, 20 having a horizontal support part (a floor plate 11, 21 and a reinforcement 12, 22) and a pair of sheathing board support parts 14a, 24a and 25a provided apart with a prescribed space directly on the horizontal support part or through a vertical member (a leg member 13, 23); a sheathing board 9, 9' provided on each sheathing board support part in the form fixture, respectively; and a width fixing member (a width fixture 17, 27) for retaining the space between both the sheathing boards.