A helical stacked integrated inductor formed by a first inducing unit and a second inducing unit includes a first helical coil and a second helical coil. The first helical coil is substantially located at a first plane and includes a first outer turn and a first inner turn. The first inner turn is surrounded by the first outer turn. The first helical coil forms a part of the first inducing unit and a part of the second inducing unit. The second helical coil is substantially located at a second plane different from the first plane and overlaps the first helical coil. The second helical coil forms a part of the first inducing unit and a part of the second inducing unit. The first helical coil and the second helical coil are stacked in a staggered arrangement.