An object of this invention is to provide an image reading apparatus capable of reading an original image at high speed. And other object is to provide an image reading apparatus in which even when heat is generated at an inverter, reading operation is not influenced. In order to achieve these object, the image reading apparatus is comprised with a scanning means including, a light source for illuminating an original, an image pickup element for receiving reflected light from the original, a cabinet and an inverter provided at a vicinity of a side face of the cabinet in parallel with a direction of moving the light source for driving the light source, a communicating means provided at a vicinity of a side face of the cabinet opposed to the side face at the vicinity of the inverter and a cooling fan for cooling an interval between the inverter and the communicating means.