A positioning apparatus comprising: an apparatus body; a draw-out portion configured to be drawn out from and attached to the apparatus body; and a positioning mechanism configured to position the draw-out portion at an attachment position with respect to the apparatus body, wherein the positioning mechanism comprises: a first engaging portion provided in one of the apparatus body and the draw-out portion; and a first engaged portion provided in another of the apparatus body and the draw-out portion and configured to determine a position of the draw-out portion in an attachment direction by engaging with the first engaging portion, the first engaged portion including an inclined surface and a positioning surface, the inclined surface being configured to contact the first engaging portion, the positioning surface being configured to position the draw-out portion in the attachment direction at the attachment position, and characterized in that the inclined surface is inclined downward toward a downstream side in the attachment direction and causes a component force in the attachment direction to act on the draw-out portion on a basis of a weight of the draw-out portion such that the positioning surface is pressed against the first engaging portion in a state in which the inclined surface contacts the first engaging portion. an apparatus body; a draw-out portion configured to be drawn out from and attached to the apparatus body; and a positioning mechanism configured to position the draw-out portion at an attachment position with respect to the apparatus body, wherein the positioning mechanism comprises: a first engaging portion provided in one of the apparatus body and the draw-out portion; and a first engaged portion provided in another of the apparatus body and the draw-out portion and configured to determine a position of the draw-out portion in an attachment direction by engaging with the first engaging portion, the first engaged portion including an inclined surface and a positioning surface, the inclined surface being configured to contact the first engaging portion, the positioning surface being configured to position the draw-out portion in the attachment direction at the attachment position, and a first engaging portion provided in one of the apparatus body and the draw-out portion; and a first engaged portion provided in another of the apparatus body and the draw-out portion and configured to determine a position of the draw-out portion in an attachment direction by engaging with the first engaging portion, the first engaged portion including an inclined surface and a positioning surface, the inclined surface being configured to contact the first engaging portion, the positioning surface being configured to position the draw-out portion in the attachment direction at the attachment position, and characterized in that the inclined surface is inclined downward toward a downstream side in the attachment direction and causes a component force in the attachment direction to act on the draw-out portion on a basis of a weight of the draw-out portion such that the positioning surface is pressed against the first engaging portion in a state in which the inclined surface contacts the first engaging portion.