Seismic isolation device

This seismic isolation device is capable of widely optimizing a damping force exhibited by a damper against shaking of various magnitudes ranging from huge earthquakes to small and medium scale earthquakes, and capable of reducing, as much as possible, response acceleration generated in an object to be seismically isolated. The seismic isolation device comprises: a fixed part (2); a movable part (3) on which the object to be seismically isolated is placed, and which is disposed on the fixed part; a support guide mechanism (4) that allows horizontal movement of the movable part relative to the fixed part, and includes a track member and a moving block that reciprocates along the track member; a damper unit (5) that exerts a reaction force against a motion of the movable part relative to the fixed part; and an elastic recovery member (6) that causes the movable part to return to an initial position on the fixed part. The damper unit (5) is constituted by a first damper (50) disposed on the fixed part, and a sec