In this study, we evaluated the radiation hardness of SiC Buried Gate Static Induction Transistors (SiC-BGSITs) and Si-based switching devices up to the absorbed dose of 10 MGy(SiO2). The on-voltage Von of Si-IGBT degraded excessively at the early stage of the irradiation (>~0.1 MGy(SiO2)) due to the bulk damage produced by Compton electrons like the gain degradation in Si bipolar transistors. The threshold voltage Vth of Si-MOSFET was very sensitive against the radiation due to the competing mechanism between the generation of the hole traps in the gate SiO2 and the SiO2/Si interface states. Moreover, the breakdown voltage VBR and leak current Ileak of MOSFET degraded significantly against the absorbed dose. While, the electrical properties of SiC-BGSIT was very stable even after the irradiation of 10 MGy(SiO2).