The present invention is transportable economically in a flat state, and easy to attach and detach, and can provide a curved surface simply while maintaining decoration and strength without craftsmanship. Slits are provided on a rectangular board panel comprising two or more layers of a hard material and a soft material. Two or more layers comprising a hard material and a soft material are laminated on a rectangular board panel, and slits having a length of ½ to ¾ of the vertical side are provided thereto. The use of slits makes formation of curved surfaces easy. Since there is no need to reinforce the outside to maintain the strength thereof, the board panel can be removed easily. Even if in external pressure is applied to the board panel, the flexibility of the hard material divided by the slits and the elastic characteristic of the soft material cause the pressure to be dispersed and absorbed.