An image forming apparatus includes: an attachment unit configured to receive at least one voltage and being replaceable with a test tool, a controller for controlling operation of a plurality of voltage generating circuits, a current detecting section and a deciding section. The controller is configured to control a first voltage generating circuit so as to generate a test voltage and so as to apply the test voltage through a first voltage line, the test tool, and a second voltage line to a second voltage generating circuit. The deciding section is configured to, upon a detection current corresponding to the applied test voltage and detected by the current detecting section being equal to or greater than a first predetermined value, decide that the predetermined voltages are to be normally applied through the respective first and second voltage lines to the attachment unit.