A heating device includes first and second heating rollers and first and second pressing rollers. The first pressing roller and the second heating roller forms a first unit, and the second pressing roller and the first heating roller forms a second unit that is rotatable about a rotational axis relative to the first unit. The heating device also includes an eccentric shaft unit disposed on one of the first unit and the second unit and extending in a direction parallel to the rotational axis, a rotational position of an eccentric portion of the eccentric shaft unit being changeable, and an engaging unit disposed on the other one of the first unit and the second unit, and configured to engage with the eccentric shaft, a position of the second unit relative to the first unit being adjusted when the rotational position of the eccentric portion of the eccentric shaft unit is changed.