To provide a high pressure gas storage facility in which leak of stored gas can be detected at high precision, at low cost, and without limit to applicable conditions.

Monitoring holes 5, 5, etc., are provided at positions around an outer surface of a lining member 3, and the monitoring holes 5, 5, etc., are formed in such a way that groundwater w in bedrock R can be inserted inside. Pitot tubes 7, 7, etc., capable of measuring groundwater pressure inside the monitoring holes 5, 5, etc., are provided.