To efficiently display a base isolation function even when an upper structure is light as a private housing, etc., and to miniaturize and lighten it in simple structure for a base isolation device devised to restrain swinging of an upper part structure against an earthquake.

It is furnished with an upper plate 1 connected to an upper part structure, a lower plate 2 provided against a lower side of the upper plate 1 and to be connected to a foundation, a support pillar 5 fixed so as to extend in the vertical direction on a lower surface except for an outer peripheral part of the upper plate 1 and a sliding member 6 provided on a lower end part of this support pillar 5 free to slide the aforementioned upper plate 1 with the support pillar 5 against the lower plate 2 relatively in the horizontal direction, and outer peripheral part overall peripheries of the upper plate 1 and the lower plate 2 are elastically connected to each other by a cylindrical rubber member 8 which extends when the upper plate 1 slides relatively in the horizontal direction against the lower plate 2 are elastically connected to each other.