An ink jet printing head, comprising: a head portion including nozzles, pressure chambers which store ink and communicate with the nozzles, and driving elements which pressurize the ink in the pressure chambers to discharge ink drops from the nozzles; an ink tank disposed over the head portion to accommodate ink which is supplied to the pressure chambers of the head portion; a first rigid circuit board on which is mounted an image-data control unit for processing image data and outputting an image-data signal; a second rigid circuit board on which is mounted a driving element driver unit to outputting a driving waveform signal to the driving elements of the head portion in accordance with the image-data signal output from the first rigid circuit board; a flexible printed circuit board arranged to electrically interconnect the first rigid circuit board and the second rigid circuit board; and a connector attached to the first rigid circuit board at an end portion thereof that is opposite to the flexible printed circuit board, the connector being connected to the image-data control unit so that the image-data control unit is connectable to a host board through the connector, wherein the connector is disposed on a top surface of the ink tank, the first rigid circuit board is disposed on a side of the ink tank, the second rigid circuit board is disposed between the ink tank and the head portion, and the flexible printed circuit board is disposed in a bent condition between the first rigid circuit board and the second rigid circuit board, so that the flexible printing circuit board functions to buffer movement of the first rigid circuit board when connected to the host board through the connector. a head portion including nozzles, pressure chambers which store ink and communicate with the nozzles, and driving elements which pressurize the ink in the pressure chambers to discharge ink drops from the nozzles; an ink tank disposed over the head portion to accommodate ink which is supplied to the pressure chambers of the head portion; a first rigid circuit board on which is mounted an image-data control unit for processing image data and outputting an image-data signal; a second rigid circuit board on which is mounted a driving element driver unit to outputting a driving waveform signal to the driving elements of the head portion in accordance with the image-data signal output from the first rigid circuit board; a flexible printed circuit board arranged to electrically interconnect the first rigid circuit board and the second rigid circuit board; and a connector attached to the first rigid circuit board at an end portion thereof that is opposite to the flexible printed circuit board, the connector being connected to the image-data control unit so that the image-data control unit is connectable to a host board through the connector, wherein the connector is disposed on a top surface of the ink tank, the first rigid circuit board is disposed on a side of the ink tank, the second rigid circuit board is disposed between the ink tank and the head portion, and the flexible printed circuit board is disposed in a bent condition between the first rigid circuit board and the second rigid circuit board, so that the flexible printing circuit board functions to buffer movement of the first rigid circuit board when connected to the host board through the connector.