To considerably increase the reuse frequency of a form to reduce a construction cost in view of a problem that the reuse frequency of the form is reduced by the easy exfoliation of a paint film applied to the surface of the form, and to reduce the degree of the form becoming industrial waste.

Alumite treatment is applied to an aluminum forming base of this form constituted using an aluminum plate for the forming base for placing and forming concrete, and a paint film is applied to the upper surface.