An image forming apparatus comprising a plurality of devices driven by power and configured to be operated in: 1) a standby mode in which the image forming apparatus stands by a start of an image formation; or 2) a power saving mode in which power supply to a part of the plurality of devices is stopped so that the power consumption of the image forming apparatus in the power saving mode is reduced compared with that of the image forming apparatus in the standby mode. The image forming apparatus further including a door which is opened when consumable material is supplied, and a door opened/closed sensor configured to detect the door opening or door closing.