To simplify working for the installation of a base isolation structure for a building and to easily maintain and manage the base isolation structure by setting an inclined angle of an inclined surface of a support member to a large value.

A base isolation structure for a building incorporates a roll bearing means 6 which is interposed between a foundation 2 and a building 4 so as to support the building 4 which is therefore movable in a horizontal direction. In this arrangement, the roll bearing means 6 is mainly composed of an upper and lower support plate 10, 8 which are fixed respectively to the foundation 2 and the building 4, and a ball 12 adapted to roll along the upper and lower support plats 8, 10 when the foundation 2 and the building 4 are displaced relative to each other. The outer surface of at least one of the upper and lower plate 10, 8 and the ball 12 is covered thereover with a rubber material 14 in order to set a virtual rolling frictional coefficient of the ball 12 in a range from 0.005 to 0.10.