A fixing device includes a heating rotating body driven by a motor, a pressing member, a biasing unit, a switching unit that receives rotational power of the motor in order to either separate the pressing member and the heating rotating body or to allow the biasing unit to press the pressing member and the heating rotating body together, a power transmission mechanism that transmits the rotational power of the motor to the switching unit over a first path or a second path, the first path having a larger reduction ratio, and a transmission control unit that establishes and cuts off transmission of rotational power of the motor to the switching unit by the power transmission mechanism and that includes a path selection unit that selects the first path during separation and the second path during pressing by the switching unit.