An image forming apparatus includes a conveyor to convey a sheet medium, a print engine to form an image on the sheet medium, a cutter to cut the sheet medium, a signal output device, and a controller. The cutter includes a first blade, a second blade, and a moving device to move at least one of the first and second blades. The controller receives, from the signal output device, a signal indicating a variation over time in a value correlated with a moving load for the at least one blade, and determines, based on the received signal, which state the sheet medium is in among a plurality of states including a first state where the sheet medium is cut normally, a second state where there is an abnormality in cutting the sheet medium, and a third state where there is a different abnormality in cutting the sheet medium.