PURPOSE: To properly arrest the upper part of an independent type tank set in a cryogenic liquefied gas transporting ship, particularly set inside it.

CONSTITUTION: A top anchor 3 is structured on the upper surface of an independent type cryogenic liquefied gas tank set inside a ship so that an anchor projected member 3a provided with an upper deck lower side beam material 5 is fitted closely into a clearance between anchor recessed members 3b and 3b fixed in pair and apart from each other. When cryogenic liquefied gas is filled into the tank 1, a mutual clearance between the anchor recessed members 3b and 3b is also reduced as the thermal contraction of tank walls. As a result, a force to tighten the anchor projected member 3a is produced, and the upper part of the tank 1 is arrested accurately when a hull is oscillated.