In fire disaster situation, vision or LiDAR sensors can hardly be used due to smokes. To deal with this environment, the localization methods using UWB signals have been researched. In this paper, the UWB-IMU sensor fusion-based localization algorithm designed to be robust in NLOS (non-line-of-sight) environment is proposed. When UWB sensors are in NLOS situation, the TOA of the signal is increased. The NLOS factor of the UWB is calculated using IMU measurement. The RMSE error of estimated trajectory is about 10 cm compared to the ground truth.