In order to test the existence of the sterile neutrino, NEOS experiment was performed from August 2015 to May 2016. The prompt energy spectrum from the inverse beta decay of electron antineutrino from a 2.8 GW$_\mathrm{th}$ reactor was measured at 24 m distance. The number of measured IBD candidates is about 2000 per day during reactor-on period and a ratio of signal to background is about 22. The result shows no strong evidence of active-to-sterile neutrino. An exclusion-limit curve for 3+1 hypothesis is found at 90% CL. via shape-only analysis.