The authors developed a drop on demand piezoelectric line inkjet printhead composed of a monolithic structure having resolution of a 600dpi in 4.25 inch print width. The printhead is provided with plural trapezoidal regions of 1-inch width approximately, in which parallel array of rhombic pressure chambers are arranged in matrix form. The trapezoidal regions are aligned in print width direction, with their oblique side facing each other, in order to set 2,656 nozzles communication with corresponding chambers, in an area of 4.25 × 0.66 inches. This monolithic structure allows easy elongation in print width just by increasing the number of trapezoidal regions. Power consumption was reduced to less than 1/10 of that of the former models per nozzle by modifications in configuration of a piezoelectric actuator and pressure chamber. Materials of the printhead were chosen to accept various fluid chemicals. The printhead showed the reliability of over 10 billion dots per nozzle at the endurance test. Full color images were obtained with a resolution of 600 × 600 dpi and 4 grade grayscale at a paper-feeding rate of 847 mm/sec by six printheads arranged in parallel, which corresponded with aqueous inks of different colors respectively.