A ship tank and a support structure therefor, the ship tank being a horizontal type cylindrical tank configured to be mounted on a ship and to store a liquefied gas, the support structure comprising: a curved surface facing an outer peripheral surface of the tank; and a pair of support units (4A, 4B) supporting the tank on the curved surface and spaced apart from each other in an axial direction of the tank; wherein each of the pair of support units (4A, 4B) includes: a plurality of cylindrical elements arranged in a circumferential direction of the tank such that an axial direction of each of the cylindrical elements coincides with a radial direction of the tank; a plurality of inner members each holding, on the outer peripheral surface of the tank, an end portion of a corresponding one of the cylindrical elements at the tank side; and a plurality of outer members each holding on the curved surface, an end portion of a corresponding one of the cylindrical elements at an opposite side to the tank, the inner members being fixed to the tank, the outer members of a first support unit, which is one of the pair of support units (4A, 4B), being configured such that displacement of the outer members in the axial direction of the tank relative to the curved surface is restricted, and characterised in that the outer members of a second support unit, which is the other one of the pair of support units (4A, 4B), being configured to be slidable on the curved surface in the axial direction of the tank; and wherein a lubricating liner is sandwiched between the curved surface and the outer members of the second support unit. a curved surface facing an outer peripheral surface of the tank; and a pair of support units (4A, 4B) supporting the tank on the curved surface and spaced apart from each other in an axial direction of the tank; wherein each of the pair of support units (4A, 4B) includes: a plurality of cylindrical elements arranged in a circumferential direction of the tank such that an axial direction of each of the cylindrical elements coincides with a radial direction of the tank; a plurality of inner members each holding, on the outer peripheral surface of the tank, an end portion of a corresponding one of the cylindrical elements at the tank side; and a plurality of outer members each holding on the curved surface, an end portion of a corresponding one of the cylindrical elements at an opposite side to the tank, a plurality of cylindrical elements arranged in a circumferential direction of the tank such that an axial direction of each of the cylindrical elements coincides with a radial direction of the tank; a plurality of inner members each holding, on the outer peripheral surface of the tank, an end portion of a corresponding one of the cylindrical elements at the tank side; and a plurality of outer members each holding on the curved surface, an end portion of a corresponding one of the cylindrical elements at an opposite side to the tank, the inner members being fixed to the tank, the outer members of a first support unit, which is one of the pair of support units (4A, 4B), being configured such that displacement of the outer members in the axial direction of the tank relative to the curved surface is restricted, and characterised in that the outer members of a second support unit, which is the other one of the pair of support units (4A, 4B), being configured to be slidable on the curved surface in the axial direction of the tank; and wherein a lubricating liner is sandwiched between the curved surface and the outer members of the second support unit.