An apparatus for exchanging paper rolls includes a paper supply mechanism having an inclined arm and a clamp assembly for receiving and holding a first paper roll; a second-roll hanger assembly arranged above the paper supply mechanism for receiving and holding a second paper roll; a slide rail arranged between the paper supply mechanism and the second-roll hanger assembly; an elevating assembly movably mounted to the slide rail; and a driving assembly for driving the elevating assembly to move along the slide rail. The elevating assembly picks up the second paper roll from the second-roll hanger assembly. To exchange the first paper roll with the second paper roll, the clamp assembly pushes the first paper roll away from the paper supply mechanism, and the elevating assembly lowers down along the slide rail to place the second paper roll in the paper supply mechanism.