Image forming apparatus

An image forming apparatus comprising:

• a heating device including a heating member having a plurality of heat generating members which independently generate heat on an elongated substrate, a moving member which moves in contact with the heating member, and a pressing member which forms a nip portion together with the heating member through the moving member and thereby heats an image on a material to be heated while sandwiching and conveying the material to be heated by the nip portion;
• a feeding device which feeds the material to be heated to said heating device;
• and
• control means which controls a heating timing of the heating member and a feeding timing of feeding the material to be heated fed by said feeding device,
• wherein in a case of continuously forming images onto the material to be heated, with respect to a turn-on time ratio defined by a heat generation amount allocated to a first heat generating member among the plurality of heat generating members and a heat generation amount allocated to a dependent heat generating member which dependently generates heat on the first heat generating member, said control means changes the turn-on time ratio in accordance with a size of the material to be heated and determines the feeding timing of the material to be heated fed by said feeding device according to temperature distribution of said heating device in a longitudinal direction of the heating member perpendicular to a conveying direction in which the material to be heated is conveyed.