A structure for a tank dome flange section, configured so as to reduce a rise in the temperature of low-temperature liquefied gas stored within a tank body section. A structure (21) for a tank dome flange section provided to a liquefied gas tank which comprises: a tank body section for storing low-temperature liquefied gas; a tank dome (3) provided at the upper part of the tank body section; a flange section (22) protruding substantially horizontally from the tank dome (3); a tank cover (6) for covering the tank body section with a space (5) therebetween; and an expansion rubber section (11) provided between the flange section (22) and the upper opening edge of the tank cover (6) and sealing the space (5). The structure (21) for a tank dome flange section is configured in such a manner that an input heat suppression material section consisting of fiber reinforced plastic is provided to a predetermined portion of the flange section (22), the predetermined portion being located between at least the sidewall (3a) of the tank dome (3) and the expansion rubber section (11).
