The series of uranium monopnictides has been investigated by many researchers with interest in the change of the 5f electron nature from itinerancy in UN to localization in USb and UBi. However, the lack of de Haas van Alphen (dHvA) effect measurements in this series did not allow accurate information to be obtained for the ground state of the 5f electronic structure. This situation is clearly due to the difficulty in getting high quality single crystals in this series. We succeeded in growing a single crystal of USb with high quality by careful annealing and by using purified uranium metal, and observed a dHvA signal in USb for the first time. We report in detail our crystal-growing process and the results of dHvA effects, and discuss the 5f electron nature in USb.