To form a section stool from stick paper boards such as corrugated cardboards.

Concerning this sectional stool, a body 5 is formed from materials for body provided by cutting and forming the thick paper board so as to have prescribed planar forms. Such a thick paper board member is folded and worked so as to be composed of two right triangular parts 55 and 55°. The body 5 in the form of isocceles triangle is formed by bonding these two right triangular parts 55 and 55' so as to link vertical wall parts 11 and 11'. A stay 6 is formed by folding and working a diamond-shaped thick paper board member (material for stay) into two. Such a stay 6 is inserted into slit grooves 111 and 155 provided at inclined wall parts 14 and 14' and vertical wall parts 11 and 11' of the body 5, and the both are integrated (assembled). Thus, weight reduction is attained and a certain degree of strength/rigidity can be provided as well. Then, resources can be recycled.