An ink-jet recording head maintenance device, comprising: a wiper that is used to wipe an ink ejection surface of an ink-jet recording head that ejects ink on a recording medium; a wiper carriage that has the wiper fixed thereto and reciprocates in a horizontal wiping direction; a supporting frame that supports the wiper carriage so that the wiper carriage is movable in the wiping direction; a wiper moving mechanism that causes the wiper carriage to reciprocate in the wiping direction along the supporting frame; and a unit ascending/descending mechanism that causes the supporting frame to ascend/descend together with the wiper carriage in such a direction as to approach or separate from the ink ejection surface, the wiper carriage being configured to ascend to a wiping position and to reciprocate from the wiping position to perform wiping of the ink ejection surface, wherein the wiper moving mechanism includes: a rack that is supported by the wiper carriage having prescribed play allowing movement of the rack with respect to the wiper carriage in an up-down direction; a wiper driving motor that is provided in the supporting frame; a rack driving gear that transmits a driving force of the wiper driving motor to the rack; and a sliding pulley that is rotatably supported by the wiper carriage and is configured to rotate in contact with the supporting frame, thereby causing reciprocating movement of the wiper carriage while retaining constant a spacing between the wiper carriage and the supporting frame; characterized in that a gear pitch retention member is provided that maintains constant a positional relationship in the up-down direction between the rack and the rack driving gear during reciprocation of the wiper carriage, and the gear pitch retention member includes: a first engagement portion that rotatably holds a rotation shaft of the rack driving gear; and a second engagement portion that slidably engages with the rack, wherein the rack includes a flange portion that protrudes horizontally along a moving direction of the wiper carriage, and the second engagement portion is in a circular shape having an outer circumferential surface that comes into contact with an upper surface of the flange portion. a wiper that is used to wipe an ink ejection surface of an ink-jet recording head that ejects ink on a recording medium; a wiper carriage that has the wiper fixed thereto and reciprocates in a horizontal wiping direction; a supporting frame that supports the wiper carriage so that the wiper carriage is movable in the wiping direction; a wiper moving mechanism that causes the wiper carriage to reciprocate in the wiping direction along the supporting frame; and a unit ascending/descending mechanism that causes the supporting frame to ascend/descend together with the wiper carriage in such a direction as to approach or separate from the ink ejection surface, the wiper carriage being configured to ascend to a wiping position and to reciprocate from the wiping position to perform wiping of the ink ejection surface, wherein the wiper moving mechanism includes: a rack that is supported by the wiper carriage having prescribed play allowing movement of the rack with respect to the wiper carriage in an up-down direction; a wiper driving motor that is provided in the supporting frame; a rack driving gear that transmits a driving force of the wiper driving motor to the rack; and a sliding pulley that is rotatably supported by the wiper carriage and is configured to rotate in contact with the supporting frame, thereby causing reciprocating movement of the wiper carriage while retaining constant a spacing between the wiper carriage and the supporting frame; characterized in that a gear pitch retention member is provided that maintains constant a positional relationship in the up-down direction between the rack and the rack driving gear during reciprocation of the wiper carriage, and a rack that is supported by the wiper carriage having prescribed play allowing movement of the rack with respect to the wiper carriage in an up-down direction; a wiper driving motor that is provided in the supporting frame; a rack driving gear that transmits a driving force of the wiper driving motor to the rack; and a sliding pulley that is rotatably supported by the wiper carriage and is configured to rotate in contact with the supporting frame, thereby causing reciprocating movement of the wiper carriage while retaining constant a spacing between the wiper carriage and the supporting frame; characterized in that a gear pitch retention member is provided that maintains constant a positional relationship in the up-down direction between the rack and the rack driving gear during reciprocation of the wiper carriage, and the gear pitch retention member includes: a first engagement portion that rotatably holds a rotation shaft of the rack driving gear; and a second engagement portion that slidably engages with the rack, wherein a first engagement portion that rotatably holds a rotation shaft of the rack driving gear; and a second engagement portion that slidably engages with the rack, wherein the rack includes a flange portion that protrudes horizontally along a moving direction of the wiper carriage, and the second engagement portion is in a circular shape having an outer circumferential surface that comes into contact with an upper surface of the flange portion.