PURPOSE: To make the construction of an underground structure easier with out taking much time to alter the indoor space.

CONSTITUTION: An outer wall 2 constituting a nearly round columnar form of a structure body 1 to be buried under the ground is divided into sections wish a fixed module along the circumferential direction. At least two partition parts 3 are set along the diametral direction at the boundary of the adjacent peripheral walls 2 in the structure 1. Unit rooms 4 are formed in the space surrounded by the parts 3 and the walls 2.