An image forming apparatus includes a main body of an apparatus, a door, an image forming unit, a sensor that outputs a predetermined signal when the door is opened, and a control unit that determines that the door is open if the predetermined signal is output from the sensor for a threshold time. When the door is opened, the image forming unit changes to a state where image formation is not executable. The control unit sets a first time as the threshold time, in a period in which the image forming unit contributes to image formation on a recording material. The control unit sets a second time longer than the first time as the threshold time, in a period in which the image forming unit does not contribute to image formation on a recording material or a period in which no image is formed on a recording material.