A toner conveying device of the present disclosure includes a conveying screw, a toner conveying pipe, and a plurality of convex portions that are formed on an inner wall surface of the toner conveying pipe. The conveying screw has a rotary shaft and a conveying vane that is formed on an outer peripheral surface of the rotary shaft. The toner conveying pipe has a circular section, and the conveying screw is rotatably disposed inside the toner conveying pipe. Each of the convex portions is formed within an area defined by half the circumference along the inner wall surface of the toner conveying pipe and supports the conveying screw so that an axial center of the rotary shaft substantially coincides with a center axis of the toner conveying pipe.