sectional view of a pressurizing section k designated in fig2 and fig4 is a fragmentary sectional view taken along the line iv iv of fig1 a printing head 1 shown in fig1 4 is for constructing a line head 11 of fig1 for printing on standard a4 size paper in this embodiment the line head 11 is formed by stacking ten printing heads 11 in layers the construction of the line head 11 will be described later in this specification comprising a substrate 2 made of such insulating material as silicon or photosensitive glass diaphragms 3 bonded to both sides of the substrate 2 each diaphragm 3 including an alkali proof glass plate 31 of which whole outside surface is covered with a metallic layer 32 made of ito fig3 for instance and bimorph cell type piezoelectric elements 4 made of pzt the printing head 1 has on its both sides 255 each dot printing sections 101 the printing head 1 is shaped in a flat plate form measuring the width of the printing head 1 in the direction of array of the dot printing sections 101 and the depth at right angles to the array the printing head 1 is approximately 220 mm wide by 18 mm deep by 12 mm thick.