[Object] To provide a fixing device in which thermal energy required for fixing a toner can be reduced to a large extent, a rising time for the fixation after energization is shortened, and the energization is not required during standby time. [Means for Solution] The fixing device is characterized by including: a preliminary fixing member A for pressurizing a toner attached to a surface of a recording medium in a thickness direction of the recording medium to preliminarily fix the toner onto the recording medium so as to remove an air existing between toner particles; and a main fixing member B for pressurizing the preliminarily fixed toner in the thickness direction of the recording medium, and for simultaneously heating and fusing the toner from a back surface side of the recording medium, to thereby mainly fix the toner onto the recording medium.