To provide a simple opening reinforcing structure capable of setting an opening in an optional position.

Reinforcement bodies 2 of a pair of reinforcements 1 with an anchorage portion are arranged obliquely with respect to a main reinforcement 12. An area A1 with no reinforcement, in which other reinforcements are not arranged, is formed between the pair of reinforcements 1; and the opening can be formed in the optional position in the area A1. Thus, since the opening 20 can be reinforced with the reinforcements 1 which are obliquely arranged on both the sides of the opening 20, the laborsaving of bar arrangement enables the opening 20 to be reinforced by a simple structure. A shear force is allowed for at the stage of a structural design, so that the opening can be set in the optional position after the application for building confirmation. Additionally, shear resistance can be clarified. This can increase the efficiency of the application for structural confirmation and prevent a delay at the start of construction.