PURPOSE: To prevent the vacuum break, caused by leak at a vacuum seal part, from spreading by disposing a valve exhibiting the sealing performance, which can be opened/closed freely during rotation, in the way of an evacuation path from a vacuum thermal insulation layer thereby preventing the vacuum of the vacuum insulation layer from deteriorating due to outgas.

CONSTITUTION: A valve 10 exhibiting the sealing performance and can be opened/closed freely during rotation is disposed in the way of an evacuation path 9 from a vacuum insulation layer divided into a plurality of independent vacuum chambers 8a-8f. The valve 10 is controlled by a valve opening/closing control means 16 to sustain the vacuum pressure in best conditions based on the output from means 15 for monitoring the vacuum pressure of the vacuum thermal insulation means. Since the continuous evacuation and sealing of the vacuum chamber can be switching at an appropriate timing even during the rotational operation, vacuum of the vacuum thermal insulation layer can be prevented from being deteriorated due to the outgas thus preventing the vacuum break, caused by partial leak at a vacuum sealed part, from spreading over the entire vacuum thermal insulation layer.