Fixing device

A fixing device for fixing a toner image onto a recording material while conveying and heating the recording material on which the toner image has been formed at a nip portion, the fixing device comprising:

• a cylindrical film;
• a heater configured to contact the film, the heater including a substrate, a first heat generating segment formed on a first surface, facing the film, of the substrate, and a second heat generating segment formed on a second surface opposite to the first surface of the substrate;
• a pressure member configured to form the nip portion with the film;
• a temperature detection unit configured to detect the second surface;
• and
• a control unit configured to supply power to the heater so that the temperature detected by the temperature detection unit becomes a target temperature,
• wherein the control unit can perform a first heater control for controlling the heater so as to supply power only to the first heat generating segment, and a second heater control for controlling the heater so as to supply power only to the second heat generating segment, and
• wherein the target temperature during performing the second heater control is higher than the target temperature during performing the first heater control.