An image forming device has a conveying member, a light source, a photo-sensor, a shutter member, a shutter driving unit, a reflecting member and a judging member. The shutter member located between the photo-sensor and the conveying member is moved between a close position and an open position. The reflecting member provided on shutter member reflects light emitted by the light source when the shutter member entirely or partially shields the light emitted by the light source and directed toward the conveying member, and an intensity of light reflected by the reflecting member and detected by the photo-sensor varying depending on a position of the shutter member. The judging member judges whether the shutter member is located at the close position or the open position and whether the conveying member is present or absent based on the intensity of the light detected by the photo-sensor.