An inkjet head comprising: a passageway member having a nozzle which is opened at a first major surface , and a pressurizing chamber which is communicated with the nozzle and is positioned on a second major surface side constituting a back surface of the first major surface ; a piezoelectric actuator substrate which is superimposed on the second major surface so as to cover the pressurizing chamber ; and a flexible printed circuit having an insulating base film , an interconnect which is provided on one major surface of the base film , and an insulating film covering the interconnect , being arranged so that the insulating film side is made to face the side of the piezoelectric actuator substrate opposite to the passageway member , and being electrically connected to the piezoelectric actuator substrate ; wherein, above the pressurizing chamber , the thickness (T) of the insulating film from the base film differs between one side where the interconnect is located and the other side opposite to the one side where the interconnect is located in a predetermined direction along the second major surface ;and wherein, a plurality of interconnects is positioned at the one side above the pressurizing chamber , and the thickness (T) of the insulating film from the base film becomes thicker at the one side than the other side . a passageway member having a nozzle which is opened at a first major surface , and a pressurizing chamber which is communicated with the nozzle and is positioned on a second major surface side constituting a back surface of the first major surface ; a nozzle which is opened at a first major surface , and a pressurizing chamber which is communicated with the nozzle and is positioned on a second major surface side constituting a back surface of the first major surface ; a piezoelectric actuator substrate which is superimposed on the second major surface so as to cover the pressurizing chamber ; and a flexible printed circuit having an insulating base film , an interconnect which is provided on one major surface of the base film , and an insulating film covering the interconnect , being arranged so that the insulating film side is made to face the side of the piezoelectric actuator substrate opposite to the passageway member , and being electrically connected to the piezoelectric actuator substrate ; wherein, having an insulating base film , an interconnect which is provided on one major surface of the base film , and an insulating film covering the interconnect , an insulating base film , an interconnect which is provided on one major surface of the base film , and an insulating film covering the interconnect , being arranged so that the insulating film side is made to face the side of the piezoelectric actuator substrate opposite to the passageway member , and being electrically connected to the piezoelectric actuator substrate ; wherein, above the pressurizing chamber , the thickness (T) of the insulating film from the base film differs between one side where the interconnect is located and the other side opposite to the one side where the interconnect is located in a predetermined direction along the second major surface ;and wherein, a plurality of interconnects is positioned at the one side above the pressurizing chamber , and the thickness (T) of the insulating film from the base film becomes thicker at the one side than the other side . <EOS>