We studied the risk analysis of fire and explosion caused by gas leak in underground-parking of gas vehicle. However, an entrance regulation of gas vehicles (H2/LPG/CNG etc.) to underground garages has not been enacted in Korea. Incase, a gas explodes in an underground parking garage placed in overcrowded residential area, such as an apartment, the scale of the damage would cause tremendous disaster. Faults of vehicle parts and management problems were evaluated by using the Failure mode and effect analysis (FMEA), which is a qualitative analysis method. The range of the damaged area by the explosion and the damage scale by the explosion pressure were analyzed by using the process hazard analysis software tool (PHAST). The study is expected to facilitate enactment of the regulation for the underground parking to restrict the gas vehicle.