Hydrogen fuel cell vehicles are expected to come into widespread use in the near future. It is therefore important to predict whether risks from hydrogen leaked caused by accident in semi-enclosed area can be avoided. In this study, CFD simulation was carried out for hydrogen leakage in typical tunnels, underground parking lot, and multistory parking garage. Simulation scenarios were as follows. The hydrogen leak rate was chosen to be the equivalent energy of allowable gasoline fuel leak in a vehicle collision test, as prescribed in FMVSS301. The ventilation rate was zero for the case of tunnels, and air exchange rate was zero or ten times per hour for underground parking lots. The analytical periods were thirty minutes for all cases. It can be said that the area of flammable mixture was limited that close to the hydrogen leaking vehicle even when there was no ventilation and become smaller when the ventilation exists. The results would therefore indicate that safety was maintained in cases of hydrogen leakage in the semi-enclosed areas even with existing equipment.