A belt conveyor unit includes a plurality of rollers around which a belt is entrained, including a first roller, a second roller disposed opposite the first roller via the belt, and a third roller other than the first roller and the second roller, and a belt alignment device including a shaft moving device to tilt a rotary shaft of the third roller upon receiving a moving force of the belt moving in a width direction of the belt in an axial direction of the rotary shaft to adjust displacement of the belt. The shaft moving device includes an axial-direction displacement member including a slanted surface that moves to a first side in the width direction of the belt along the rotary shaft upon receiving the moving force of the belt, and a fixation member to contact the slanted surface from the first side in the width direction of the belt.