To obtain a heat resistant resin composition excellent in close adhesion property to a base material and flexibility, and a fire resistant tape having a high practical utility by using the same composition, and to provide a structure for preventing a building from spreading fire capable of surely blocking the air ventilating layer by using the same tape.

This heat resistant resin composition is obtained by blending 100 pts.wt. carbonization accelerating agent 15-70 pt.wt. carbonizing component, 15-110 pt.wt. foaming agent and 100-300 pt.wt. binder. The binder has ≤2 Map modulus stretched at 100% and ≥60% breaking elongation. The fire resistant tape 1 is constituted by providing a layer consisting of the above heat resistant resin composition on the surface of a tape base. The structure for preventing a building from spreading fire, is provided by fixing the fire-resistant tape 1 at members facing to air-ventilating layer 2 of the building along the widthwise direction of the air ventilating layer 2.