A decompression heat-insulating pipe structure that can exhibit the desired heat-insulating performance and is easy to assemble. In the structure, a space between ends of inner and outer tubes is decompressed. The outer tube includes a first flange, which extends radially inward from an axially one end thereof, and a second flange, which extends radially outward from the axially other end thereof. The inner tube includes a third flange, which extends radially inward from an axially one end thereof and is opposed to the first flange at an axially inward position of the first flange, and a fourth flange, which extends radially outward from the axially other end thereof and being opposed to the second flange at an axially outward position of the second flange. First and second elastic seal members are disposed between the first and third flanges and between the second and fourth flanges, respectively.