Ink-jet printing head

An ink-jet printing head comprising a flow-passage unit and an actuator unit laminated on each other, said flow-passage unit having nozzles, pressure chambers communicating with said nozzles, respectively, and a common manifold communicating with an ink supply source, and said actuator unit being operable to apply pressure to ink in each pressure chamber, and wherein each of said pressure chambers communicates at one of opposite longitudinal ends thereof with a corresponding one of said nozzles, and at the other of said opposite longitudinal ends with said common manifold, and is formed so as to be open in one of opposite surfaces of said flow-passage unit, such that said each pressure chamber is partially defined by said actuator unit, said flow passage unit having for each nozzle one and only one flow passage for communication between said each nozzle and said common manifold through a corresponding one of said pressure chambers, wherein each of said pressure chambers has a depth of 35 μm–45 μm in a direction perpendicular to said one of opposite surfaces of said flow-passage unit.