An image forming apparatus having an image carrier; an electrostatic latent image forming device that forms an electrostatic latent image on the image carrier; a development device having a housing section that stores toner therein, a stirring device for stirring the toner inside the housing section, and a toner, carrier that develops the electrostatic latent image into a toner image by imparting the toner to the image carrier; a voltage applying device that applies a development bias voltage between the image carrier and the toner carrier; a control device that makes the electrostatic latent image forming device and the development device form a test toner image on the image carrier; and a sensing device that senses a toner adhering amount of the test toner image. The control device determines whether to make the stirring device stir the toner based upon a relation between the toner adhering amount of the test toner image and the development bias voltage that was applied by the voltage applying device for formation of the test toner image.