A maintenance device includes a wiper, a wiper carriage, a supporting frame, a wiper moving mechanism, and a unit ascending/descending mechanism. The wiper moving mechanism includes a rack supported to the wiper carriage so as to be movable in an up-down direction, a wiper driving motor provided in the supporting frame, a rack driving gear that transmits a driving force of the wiper driving motor to the rack, a sliding member that is rotatably supported to the wiper carriage and comes into contact with the supporting frame, and a gear pitch retention member 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.