An image forming apparatus includes an image forming portion, an image bearing member, a transfer member, a voltage applying portion, a detecting portion, and a controller capable of executing an operation in an adjustment mode in which a chart on which a plurality of test images are transferred by stepwise changing a test voltage applied to the transfer member by the applying portion is formed on a recording material and then a transfer voltage applied to the transfer member by the voltage applying portion during transfer of the toner image is adjusted. The controller is capable of changing a change width per level of the test voltage applied during formation of the chart[[,]] on the basis of a detection result of the detecting portion when the voltage is applied to the transfer member when the recording material on which the chart is formed is in the transfer portion.