A stacked inductor device including an 8-shaped inductor structure a stacked coil. The 8-shaped inductor structure includes a first coil and a second coil. The first coil is disposed in a first area. The first coil includes a first sub-coil and a second sub-coil, and the first sub-coil and the second sub-coil are disposed with an interval circularly with each other. The second coil is disposed in a second area, and the second coil is coupled with the first coil on a boundary between the first area and the second area. The second coil includes a third sub-coil and a fourth sub-coil, and the third sub-coil and the fourth sub-coil are disposed with an interval circularly with each other. The stacked coil is coupled to the first coil and the second coil and is stacked partially on or under the first coil and the second coil.