A fixing device includes a rotatable fixing roller, an endless fixing belt, a pressing unit having first and second pressing members that press a surface of the fixing belt against the fixing roller, a fixed support member that supports the fixing roller rotatably, a movable support member that supports the first pressing member in a fixed state and supports the second pressing member such as to be movable closer to and away from the fixing roller, a first pressure spring that presses the movable support member closer to the fixing roller, a second pressure spring that presses the second pressing member closer to the fixing roller, and a switch mechanism that switches between a first state in which the first and second pressing members are pressed against the fixing roller and a second state in which only the second pressing member is pressed against the fixing roller.