A safety study of gaseous hydrogen supply stations with 40MPa storage system is undertaken through a risk based approach. Accident scenarios are identified based on a generic model of hydrogen station. And risks of identified accident scenarios are estimated and evaluated comparing with risk acceptance criteria. Also, safety measures for risk reduction are discussed. Especially for clearance distance, it is proposed that the distance from high-pressurized equipment to site borders should be at least 6 meters. As a result of the study, it is concluded that risks of accidental scenarios can be mitigated to acceptable level under the proposed safety measures, with several exceptions. These exceptional scenarios are very unlikely to occur, but expected to have extremely severe consequence once occurred.