A head unit comprising: a plurality of print heads (23-n) that discharge liquid; and a housing (22, 31) that houses the plurality of print heads, wherein a first print head in the plurality of print heads includes a substrate that includes a first side, a second side which intersects with the first side, a first surface which has the first side and the second side, and a second surface which is different from the first surface, a first nozzle plate that includes a first nozzle row in which a plurality of first nozzles for discharging the liquid are provided in line in a direction along the first side, a connector that is provided in the first surface and to which a digital signal is input, a first integrated circuit that is provided in the first surface, that is electrically coupled to the connector, to which the digital signal is input via the connector, and that outputs an abnormality signal indicating presence or absence of abnormality of the first print head, a first flexible wiring substrate that is electrically coupled to the substrate, and a second integrated circuit that is provided on the first flexible wiring substrate, the first integrated circuit has a diagnostic circuit and is configured to diagnose the presence or absence of the abnormality of the first print head based on the digital signal input via the connector, the second integrated circuit is located between the first nozzle plate and the substrate, and the substrate is provided on an opposite side of the first nozzle plate to an ink discharge surface of the first nozzle plate from which the ink is discharged, and is arranged so that the first surface faces the first nozzle plate. a plurality of print heads (23-n) that discharge liquid; and a housing (22, 31) that houses the plurality of print heads, wherein a first print head in the plurality of print heads includes a substrate that includes a first side, a second side which intersects with the first side, a first surface which has the first side and the second side, and a second surface which is different from the first surface, a first nozzle plate that includes a first nozzle row in which a plurality of first nozzles for discharging the liquid are provided in line in a direction along the first side, a connector that is provided in the first surface and to which a digital signal is input, a first integrated circuit that is provided in the first surface, that is electrically coupled to the connector, to which the digital signal is input via the connector, and that outputs an abnormality signal indicating presence or absence of abnormality of the first print head, a first flexible wiring substrate that is electrically coupled to the substrate, and a second integrated circuit that is provided on the first flexible wiring substrate, the first integrated circuit has a diagnostic circuit and is configured to diagnose the presence or absence of the abnormality of the first print head based on the digital signal input via the connector, the second integrated circuit is located between the first nozzle plate and the substrate, and the substrate is provided on an opposite side of the first nozzle plate to an ink discharge surface of the first nozzle plate from which the ink is discharged, and is arranged so that the first surface faces the first nozzle plate.