Radiation　and　annealing　effects　of　SiC　MOSFETs　at　high　voltage　gate　bias　are　investigated.　The　oxide-trapped　charges　and　interface　traps　are　estimated.　The　results　indicate　that　the　shift　of　threshold　voltage　caused　by　the　irradiation　is　reduced　at　positive　25V　gate　bias　compared　the　shift　at　positive　12V　gate　bias.　For　the　annealing,　with　the　45V　gate　bias,　the　oxide-trapped　charges　for　irradiated　SiC　MOSFETs　are　neutralized　more　rapidly　by　high-voltage　annealing　than　thermal　annealing　and　the　threshold　voltage　can　be　recovered　to　its　original　level　in　a　few　minutes.