The corrosion behaviors of HNO3 absorption tower (diameter: 2.6 m and 2.0 m, height: 15 m, thickness of wall: 20 mm) made of rigid PVC are discussed. The specimens were cut from the outside, middle and inner layers of the tower wall, then the creep rupture strength, tensile strength, flexural strength and impact strength were measured, and also IR analyses were made. From the IR analyses, the absorption peaks of -OH and >C = O groups were caused in the outside layer and inner layer and the absorption by >C = O and nitro groups was recognized. The corrosion depths of outside and inner layer were estimated to be 250 and 500 mu m respectively by the IR absorption peak of barium stearate used as a stabilizer. As a result, it is found that PVC is quite suitable as a substitute material of stainless steel used for HNO3 production equipment.