Provided is a tank comprising a tank body and first and second reinforcement members. The tank body includes a first wall portion, a first opposing wall portion opposing to the first wall portion in a first direction, a second wall, and a second opposing wall portion opposing to the second wall in a second direction. The first reinforcement member is disposed across the first wall portion and the first opposing wall portion, the first reinforcement member having opposite ends welded to the first wall portion and the first opposing wall portion, respectively. The second reinforcement member is disposed across the second wall and the second opposing wall portion while spatially crossing the first reinforcement member, the second reinforcement member having opposite ends welded to the second wall and the second opposing wall portion, respectively.