Double-shell tank and liquefied gas carrier ship

A horizontal type cylindrical double-shell tank comprising:

• an inner shell including an inner shell main part storing a liquefied gas and an inner shell dome, the inner shell main part including a cylindrical body portion that extends horizontally and sealing portions that seal openings on both sides of the body portion, the inner shell dome protruding from the body portion of the inner shell main part;
• and
• an outer shell forming a vacuum space between the inner shell and the outer shell, the outer shell including an outer shell main part surrounding the inner shell main part and an outer shell dome surrounding the inner shell dome, wherein
• the inner shell dome and the outer shell dome are penetrated by a pipe,
• the inner shell dome includes a first peripheral wall and a first ceiling wall, and the first ceiling wall is provided with an inner shell manhole,
• the outer shell dome includes a second peripheral wall and a second ceiling wall, and the second ceiling wall is provided with an outer shell manhole at a position corresponding to a position of the inner shell manhole.