Corrosion of rebar causes a severe problem that causes extensive damage to various types of structures. While considerable research has been carried out on measuring the amount of corrosion and methods to slow the progress of corrosion, a qualitative measurement technique that can measure the amount of corrosion of reinforcing steel need to be developed. The purpose of this research is to develop a new tech-nique to measure the corrosion level of rebar using accumulated thermal data. Accumulated thermal data were gathered using infrared cam-era and digitized to distinguish the difference between various corrosion levels of rebar. The test results shows that the higher level of corro-sion displays the higher level of temperature.