Exposure device, image forming apparatus and manufacturing method for exposure device

An exposure device comprising:

• a substrate that includes a plate-shaped main body that extends in one direction, a plurality of light emitting elements that are mounted on one surface of the main body, and a heating element that is mounted on the other surface of the main body and generates heat in accordance with light emission of the light emitting elements;
• a housing that extends in the one direction, has a frame shape in which a through hole is formed, and to an inside of the through hole of which the substrate is fixed so that a thickness direction of the main body is a penetrating direction of the through hole;
• a facing member that is fixed to the housing so as to be opposed to the other surface of the main body;
• and
• a contact member that is in contact with the facing member and the heating element,
• wherein an injection portion to inject a soft member which is the contact member is formed between the substrate and the facing member on at least one of the facing member and the housing, and
• wherein when viewed a substrate side through the injection portion, the contact member covers at least partially the heating element.