An image forming apparatus includes: a photosensitive drum; a developing roller; a separation mechanism for moving the developing roller between a contacting position contacting the photosensitive drum and a separated position separated from the photosensitive drum; a first tray; a first sheet feed mechanism for feeding a sheet from the first tray toward the photosensitive drum; a first sheet sensor for detecting passage of the sheet at a prescribed position; and a controller. The controller of the image forming apparatus is configured to perform: when a printing operation is performed onto the sheet ted from the first tray, feeding the sheet in the first tray to the prescribed position and maintain the sheet; moving, on or after the first sheet sensor detects the sheet, the developing roller to the contacting position.