Image forming apparatus and image forming method

An image forming apparatus comprising:

• a fixing unit including:
• a heater including a first surface and a second surface opposite to the first surface,
• a fixing belt having a surface to which a lubricant is applied and contacting the first surface of the heater through the lubricant,
• a heat conductor contacting the second surface of the heater, and
• a pressing roller capable of pressing and rotating the fixing belt;
• a power supply configured to supply electric power to the heater;
• a first thermometer configured to measure a temperature of the heat conductor;
• and
• a controller configured to control the power supply, wherein the controller, before controlling the pressing roller to rotate, controls the power supply to supply to the heater:
• a first amount of electric power when the temperature of the heat conductor is lower than a first value,
• a second amount of electric power less than the first amount when the temperature of the heat conductor is higher than or equal to the first value.