In large cities in Japan, as the shallow underground is extremely complex use nowadays, we need to construct new infra-structures in deeper underground. Water pipelines are not exceptional. In deep underground, the water pressure exceeds, the buckling of steel water pipes is a considerable problem. To prevent the buckling, it is necessary to study the mechanism of its buckling behavior for the design of such pipelines. In this paper, the buckling behavior is mentioned from model tests using aluminum seamless cylindrical pipe with water pressure. The result of the experiment is compared with the analytical results by FEM, then the behavior of buckling is discussed.