A liquid tank and a tubular structure for liquid tank capable of suctioning an internal liquid to the last drop even when the tank is tilted to any angle are provided. The tubular structure 40 has a duct line 41 extending from a specific position 41A in the tank body 30 in a direction toward apexes, sides, or faces of the tank body 30. Ends of the duct line 41 are contacted with the apexes, the sides, or the faces of the tank body 30, and have a liquid inlet 41B. Since the inlet 41B is limited to the ends of the duct line 41, flow of the liquid in the tank body 30 has a certain directivity that the liquid enters through only the inlet 41B into the duct line 41, is transported to the specific position 41A, and is suctioned outside. In the tubular structure 40, an inner structure 45 having voids thorough which the liquid passes such as a porous body is provided. The voids have an average pore diameter with which the liquid is able to be suctioned by capillary force from the inlet 41B to the specific position 41A, and thereby increase of flow path resistance is suppressed.