The infrared thermography NDT technique is employed in exterior wall inspections conducted in accordance with the Building Standards Act, Article 12 as a non-destructive inspection method that can efficiently detect delamination defects of tiled exterior walls of buildings, in conjunction with the NDT technique based on hammering sound. Since the exterior wall survey using the infrared method is conducted outdoors, not only infrared radiation emitted from the surface of the object, but also reflected infrared radiation from the background, such as sunlight and surrounding buildings, are detected by the infrared camera. This causes an error in inspection results. This paper describes the development of a microbolometer infrared camera with sensitivity in the 5-8μm wavelength range, verification of its effectiveness in reducing background reflections on tile surfaces, and the results of nondestructive inspection of actual buildings using this camera. It was found that the reflection noise due to the sunlight or surrounding objects were drastically reduced using the 5-8μm wavelength range infrared camera.