In the present study, the relationship between the fluctuation of indium (In) composition and wavelength change involved in internal quantum efficiency of InGaN based LEDs has been investigated. The In composition of commercial InGaN based LEDs with and without annealing at 900 oC has been analyzed by using atom probe tomography (APT). The results revealed that the decrease in In composition caused by annealing at 900 oC for 30 min. exhibited the wavelength change (approximately 6.13 nm blueshift) in the photoluminescence (PL). Wavelength change in the PL of InGaN based LEDs will be discussed in terms of the composition and distribution of In in InGaN/GaN.