A deburring device, for removing burrs off an inner sidewall of a hole of a workpiece, includes a mounting seat, a first driving member, an elastic coupler, a cutter, a polisher assembly, an elastic coupler, and a controller. The first driving member is mounted on the mounting seat. The cutter is connected to the first driving member by the elastic coupler. The polishing assembly is assembled to the mounting seat and arranged opposite to the cutter, in which the controller is electrically connected to the first driving member and the polisher assembly. The controller controls the cutter to enter the hole of the workpiece and mill the inner sidewall of the hole of the workpiece to remove burrs off the workpiece, the polishing pad moves to remove burrs generated by the cutter.