To reinforce bending yield strength by sticking a specific carbon fiber sheet to the upper portion than the plastic hinge zone of the base section of a columnar body, sticking an Aramid fiber sheet or a carbon fiber sheet having specific breaking strain to the plastic hinge zone, and sticking it to the carbon fiber sheet on the upper portion.

A carbon fiber sheet 4 having the tensile elastic modulus equal to or larger than that of reinforcing bars is stuck to the upper portion 3 than the plastic hinge zone 2 of the base section of a reinforced concrete columnar body 1 along the axial direction of the columnar body 1. An Aramid fiber sheet or a carbon fiber sheet 5 having the breaking strain of 20000μm or above is stuck to the plastic hinge zone 2 of the base section of the columnar body 1 along the axial direction of the columnar body 1. The carbon fiber sheet 4 on the upper portion 3 than the plastic hinge zone 2 and the Aramid fiber sheet or carbon fiber sheet 5 on the plastic hinge zone 2 are stuck or integrated together. Even if large bending stress is applied to the columnar body 1 when a large-scale earthquake occurs, no rupture of fibers occurs at the time of a final breakdown.