PURPOSE: To improve the appearance and reduce the cost by sticking a pattern board applied with an irregular pattern to a thin plate made of a synthetic resin to an outside formwork, transferring the pattern to concrete, and reuse the pattern board.

CONSTITUTION: A pattern board 13 applied with an irregular pattern to a non- foaming synthetic resin thin plate or waterproof paper by vacuum molding is fixed to an outside concrete formwork 12, concrete is placed in the formwork 12, and the irregular pattern is transferred to the surface of the concrete. The formwork 12 is released after the concrete is hardened, deposits on the surface are removed, and the pattern board 13 is repeatedly used multiple times. The general formwork 12 is used as it is, and the pattern board 13 can be manufactured at a low cost. The appearance of the concrete surface is improved, and the execution can be efficiently conducted.