A tip dresser comprising: a rotary cutter configured to simultaneously cut respective tip ends of a pair of spot-welding electrode tips, arranged to face each other on both sides in its rotation axis direction, by rotating a pair of cutting edges which are provided for the respective tip ends; a body case comprising a plate-like protruding portion, wherein the plate-like protruding portion is configured to house the rotary cutter; and a cover case configured to prevent chips shaved off by cutting work with the rotary cutter from scattering, wherein the rotary cutter includes: a pair of recessed receivers arranged symmetrically in the rotation axis direction to receive the respective tip ends of the electrode tips so that the center axis of the electrode tips agrees with the rotation axis while the receivers are cutting the respective tip ends of the electrode tips; and a through portion running in the rotation axis direction to provide an opening that communicates with the respective recessed receivers, the plate-like protruding portion has through holes (2c, 2d) associated with respective recessed receivers of the rotary cutter, the cover case has an opening and is fixed to the plate-like protruding portion so as to cover one of the pair of recessed receivers such that the opening is aligned with the through hole associated with the one recessed receiver of the rotary cutter; characterised in that the tip dresser includes a cover plate having, at its center portion, an electrode tip insertion hole, of which the shape corresponds to the profile of the electrode tips, the cover plate being fixed to the other side of the rotary cutter so as to cover the open end of the other recessed receiver of the rotary cutter and so as to be fitted into the through hole associated with the other recessed receiver, the cover plate being configured to rotate along with the rotary cutter. a rotary cutter configured to simultaneously cut respective tip ends of a pair of spot-welding electrode tips, arranged to face each other on both sides in its rotation axis direction, by rotating a pair of cutting edges which are provided for the respective tip ends; a body case comprising a plate-like protruding portion, wherein the plate-like protruding portion is configured to house the rotary cutter; and a cover case configured to prevent chips shaved off by cutting work with the rotary cutter from scattering, wherein the rotary cutter includes: a pair of recessed receivers arranged symmetrically in the rotation axis direction to receive the respective tip ends of the electrode tips so that the center axis of the electrode tips agrees with the rotation axis while the receivers are cutting the respective tip ends of the electrode tips; and a through portion running in the rotation axis direction to provide an opening that communicates with the respective recessed receivers, a pair of recessed receivers arranged symmetrically in the rotation axis direction to receive the respective tip ends of the electrode tips so that the center axis of the electrode tips agrees with the rotation axis while the receivers are cutting the respective tip ends of the electrode tips; and a through portion running in the rotation axis direction to provide an opening that communicates with the respective recessed receivers, the plate-like protruding portion has through holes (2c, 2d) associated with respective recessed receivers of the rotary cutter, the cover case has an opening and is fixed to the plate-like protruding portion so as to cover one of the pair of recessed receivers such that the opening is aligned with the through hole associated with the one recessed receiver of the rotary cutter; characterised in that the tip dresser includes a cover plate having, at its center portion, an electrode tip insertion hole, of which the shape corresponds to the profile of the electrode tips, the cover plate being fixed to the other side of the rotary cutter so as to cover the open end of the other recessed receiver of the rotary cutter and so as to be fitted into the through hole associated with the other recessed receiver, the cover plate being configured to rotate along with the rotary cutter.