The printing device is ink jet, parallel or serial-parallel type and comprises a plurality of ejection modules each of which with ejection chambers suitable for containing ink and with associated relative heating elements for ink ejection control. The device includes a support and a nozzle plate common to the modules, and in which the support includes a base plate of rigid material that defines through its thickness a feeding duct for the ink which, in use, is substantially parallel to the line of printing (X axis) and the ejection modules are fixed side by side on the base plate and with the ejection chambers arranged in a line in the same direction (X axis), is a hydraulic, tight connection with the feeding duct. The nozzle plate is fixed on the ejection modules constituting an upper, hydraulically tight, closing surface, for the chambers and comprises a plurality of ejection nozzles in a line, in turn in hydraulic connection with corresponding cells of the modules.