A fixing device includes a detection device. The detection device includes an actuator and a roller. The roller includes a sheet contact part. The roller is supported by the actuator in a movable manner between a first roller position and a second roller position. When the roller is positioned at the first roller position, the sheet contact part juts out from the actuator as viewed in an axial direction of the roller. When the roller is positioned at the second roller position, the sheet contact part overlaps with the actuator as viewed in the axial direction of the roller.