Preheating device and image forming apparatus

A preheating device for heating a continuous medium that is continuous in a transport direction in which the continuous medium is transported, the preheating device being disposed upstream of a fixing device in the transport direction, the fixing device fixing an image, which has been transferred to the continuous medium, to the continuous medium, the preheating device comprising:

• a heating member configured to heat the continuous medium by using heat supplied from a heat source and to contact one surface of the heat source;
• and
• a movement unit comprising a cam or a pair of transport members, wherein the movement unit is configured to move at least one of the continuous medium and the heating member in a direction in which the continuous medium and the heating member move relatively closer to each other or in a direction in which the continuous medium and the heating member move relatively away from each other,
• wherein all of the heat source is disposed in a heater-containing space, and
• wherein, on the basis of predetermined heating conditions, the movement unit configured to move at least one of the continuous medium and the heating member in the direction in which the continuous medium and the heating member move relatively closer to each other if the heating conditions are satisfied, and the movement unit configured to move at least one of the continuous medium and the heating member in the direction in which the continuous medium and the heating member move relatively away from each other if the heating conditions are not satisfied.