3D automatic drawing method of reinforced concrete structure is proposed to represent each reinforcing bars and concrete from the results of the structural design. The element arrangement of each reinforcing bar must be determined based on the design standard and specification. In the process of obtaining the drawing data, 3D positions of the reinforcing bars and the amounts of required reinforcing bars are calculated and are recorded in the storage simultaneously. Especially, reinforcing bars must be placed without crossing or contacting with them each other. 3D structural drawings were made automatically using the CAD software based on the previously designed positions of reinforcing bars. The reinforcing element data was represented as the tabular form. A typical thick RC slab with piles and a drain pit placed on the soil foundation was employed to explain the proposed methodology. The proposed method enables us to manage the construction process using 3D drawings as the virtually constructed digital twin structure. And the laborious work to estimate the amount of the reinforcing bars and to draw the construction data was reduced.