To inexpensively and quickly provide a panel having a great circular arc, which is gradually requested in construction interior trimming, display design, and furniture manufacturing.

A plurality of panels can be formed at the same time using a base material grooved in the part or the whole surface of the one side as the main material of the panel, and using a compression device in which a template capable of being produced with a simple machine tool is made a forming die. Thereby, the panel with the great circular arc can be reduced in cost and provided quickly.