PURPOSE: An LNG storage tank is provided to improve the buckling strength of an insulation box and to easily check gas leakage by monitoring vacuum pressure. CONSTITUTION: An LNG storage tank(100) comprises a primary insulation box(130) and a secondary insulation box(140). The primary insulation box is installed between a primary bulkhead(110) and a secondary bulkhead(120). The primary insulation box is filled with insulation materials. A gap where the primary insulation box is installed between the primary and secondary bulkheads is vacuumed. The secondary insulation box is filled with the insulation materials and has atmospheric pressure. [Reference numerals] (160) Display unit; (180) Control unit
