To provide a vertical seismic isolation device capable of providing a seismic isolation object with vertical seismic isolation which has a minimum pressure receiving area defined by a cylinder directly connected to the seismic isolation object and does not use highly compressed air.

A vertical seismic isolation device 1 comprises: a cylinder 10 which increases or decreases pressure of hydraulic oil 12 stored therein; and a tank 30 which has a first chamber 31 to store the hydraulic oil 12 and a second chamber 32 to store compressed air 34 and converts force applied to a first plane 331a by the hydraulic oil 12 into the force applied to a second plane 332a by compressed air 34 in a manner that enables the first plane 331a, of an intercalated portion 33 arranged in the first chamber 31, to receive pressure from the hydraulic oil 12 and enables the second plane 332a, of the intercalated portion 33 arranged in the second chamber 32, to receive the pressure from the compressed air 34. A second pressure receiving area through which the second plane 332a receives the pressure is larger than a first pressure receiving area through which the first plane 331a receives the pressure along a sliding direction.