An image forming portion carries out image formation processing where an image is formed an a recording medium on the basis of image information and is provided with a drive motor portion for driving predetermined mechanisms employed in the image formation processing and a control sensor portion for controlling the predetermined mechanisms, and a power source portion for supplying electric power to the image forming portion. A start instruction detecting portion detects start instruction to start the image formation processing, and a power source control portion inhibits the power source portion from supplying the electric power to the drive motor portion and/or the control sensor portion before the start instruction detecting portion detects the start instruction when the image formation processing is not being performed.