A fixing device includes first and second rollers, a pressure adjustment mechanism, a drive input gear, a ratchet mechanism, and a transmission mechanism. The pressure adjustment mechanism changes a pressing posture of the first and second rollers. The drive input gear device receives a torque of a first rotational direction around an axis of the gear device and another toque of a second rotational direction. The ratchet mechanism, when the drive input gear device receives the torque of the first rotational direction, transmits the torque to the first roller, and in the case of the torque of the second rotational direction, suspends a torque transmission. When the drive input gear device receives the torque of the second rotational direction, the transmission mechanism exerts a driving force to the pressure adjustment mechanism. The drive input gear device includes a housing portion housing a part of the ratchet mechanism.