The JSNS2 experiment aims to search for the existence of sterile neutrinos at J-PARC. A 1 MW beam of 3 GeV protons incident on a spallation neutron target produces an intense neutrino beam from muon decay at rest. The experiment searches for muon anti-neutrino to electron anti-neutrino oscillations which are detected by the inverse beta decay interaction, followed by gammas from neutron capture on Gd. There was a physics run in 2021, which took 11.9% of approved POT. Using the 2021 data, sterile neutrino candidates are selected, and the backgrounds are analyzed. The background samples are extracted from sideband events of sterile neutrino, and the effect of pulse shape discrimination(PSD) on the background events is studied. Preliminary results on the backgrounds are shown in this presentation.