To obtain assembling operability by providing a hanging holding part capable of hanging and holding with a band form sideward of reinforcing material, hanging and holding the band form to the hanging holding part, and thereafter attaching it thereto.

A hanging holding part 9 is formed sideward of reinforcing material 2 constituted of a plurality of main bars 5 and gate type spacers 6. Band forms 3, 4 such as net material are hung and held on the hanging holding part 9, thereafter they are attached thereto, and made a form device 1. And solidification material such as mortar is sprayed between the band forms 3, 4. Thus, since the band forms are attached thereto thereafter, they can correspond to a curved slope frame, and arbitrary shaped slope frames can be constructed.