Apparatus for washing a glazing head, the glazing head being situated above a straight conveying line on which ceramic tiles or slabs are made to advance, and with the head being aimed at uniformly coating with liquid ceramic glaze a part or all of the upper surface of said ceramic tiles or slabs, with said glazing head comprising: a hopper including two parts, a first part and a second part, movable with respect to each other; operating means, designed to set an operating position of said hopper, in which said first part and second part are suitably moved close to each other to define a calibrated outlet slot for said liquid ceramic glaze, and also designed to set said hopper in an open position, in which said first part and second part are moved away from each other, with said apparatus characterized in that it includes: - lifting means, connected to said glazing head and provided for moving vertically the latter between at least two characteristic positions, respectively a lowered working position, in which said calibrated outlet slot is located at a predetermined height from said ceramic tiles or slabs passing below, and a raised maintenance position, in which said glazing head is placed at an appropriately raised height from said transport line; - a cleaning unit, situated transversely to said straight conveying line and parallel to said glazing head; - spraying means, provided in said cleaning unit to dispense cleaning fluid under pressure inside said hopper, when it is in its said open position; - moving means, connected to said cleaning unit, provided for moving the latter in a longitudinal direction with respect to said straight conveying line, between a rest position, in which the same cleaning unit is spaced from said glazing head, so as to allow the latter to be placed in its lowered working position, and a washing position, in which said cleaning unit is located below said glazing head, previously placed in the afore-mentioned raised maintenance position, and with said hopper being in its open position, so that said spraying means are substantially centred with respect to said hopper, so that the cleaning liquid ejected therefrom hits and washes the respective internal walls of said hopper. - lifting means, connected to said glazing head and provided for moving vertically the latter between at least two characteristic positions, respectively a lowered working position, in which said calibrated outlet slot is located at a predetermined height from said ceramic tiles or slabs passing below, and a raised maintenance position, in which said glazing head is placed at an appropriately raised height from said transport line; - a cleaning unit, situated transversely to said straight conveying line and parallel to said glazing head; - spraying means, provided in said cleaning unit to dispense cleaning fluid under pressure inside said hopper, when it is in its said open position; - moving means, connected to said cleaning unit, provided for moving the latter in a longitudinal direction with respect to said straight conveying line, between a rest position, in which the same cleaning unit is spaced from said glazing head, so as to allow the latter to be placed in its lowered working position, and a washing position, in which said cleaning unit is located below said glazing head, previously placed in the afore-mentioned raised maintenance position, and with said hopper being in its open position, so that said spraying means are substantially centred with respect to said hopper, so that the cleaning liquid ejected therefrom hits and washes the respective internal walls of said hopper.