An image forming apparatus includes a case, a medium cassette that is detachably installed to the case selectively loading types of mediums, a sensor that detects first and second states of the medium cassette, the first status being determined when the medium cassette installed in the case moves in a detaching direction, and the second state being determined when the medium cassette moves in an installing direction, an output part that outputs medium setting promotion information for setting medium type information, and a control part that controls an image forming process based on a detection result by the sensor and the medium type information. When the second state is detected before a predetermined time passes from a detection of the first state by the sensor, the control part performs the image forming process by omitting an output of the medium setting promotion information, and when the second state is detected after the predetermined time has passed from the detection of the first state, the control part performs the image forming process after outputting the medium setting promotion information.