In this study, the increment in the breakdown voltage of a SiC junction barrier Schottky (JBS) diode under negative bias stress (NBS) is investigated. However, when the SiC JBS exhibits an increase in breakdown voltage after NBS, its forward characteristic does not change. The variation in breakdown voltage increases under a higher stress voltage that is close to the breakdown voltage of SiC JBS without stress. Furthermore, the variation in breakdown voltage increases with a higher compliance current and at lower NBS temperature. The electric field of SiC JBS under NBS is simulated to clarify the variation in breakdown voltage under NBS. The electrical characteristics and the simulation of the electric field under NBS demonstrate that the increase in the breakdown voltage of SiC JBS after NBS is induced by the electron injection in the oxide layer of edge termination.