To enhance profitability by reducing the numbers of air sending fans and air sending ducts in an image forming apparatus.

This image forming apparatus has a device main body, an image forming means having a photoreceptor provided at the inside of the device main body, an electrifying device to electrify the surface of the photoreceptor, an exposure unit to form an electrostatic latent image on the surface of the photoreceptor, a developing unit to form a toner image by developing the electrostatic latent image on the surface of the photoreceptor and a transfer unit to transfer the toner image on the surface of the photoreceptor to recording paper, the air sending fan provided at the inside of the device main body and to discharge air at the inside of the device main body to the outside of the device main body, the air sending duct to guide the air sent from the air sending fan to the outside of the device main body, a filter which is provided at the air sending duct and through which the air flowing through the air sending duct passes and a power source unit having a power source circuit element and a heat sink and provided at the inside of the device main body in a state in which the heat sink is projected to the inside of the air sending duct.