There is provided a head module including: a head which has an inlet, a plurality of nozzles, and a plurality of driving elements, and in which the nozzles are aligned in rows in a longitudinal direction of a nozzle surface orthogonal to a attaching/detaching direction of the head module; a plurality of driver ICs; a heat spreader; a flexible substrate; and a rigid substrate. In the attaching/detaching direction, the driver ICs are arranged between the head and the heat spreader; the rigid substrate and the head are arranged side by side in the attaching/detaching direction; the rigid substrate and the heat spreader are arranged side by side in a short direction of the nozzle surface; and the rigid substrate has a thickness along the short direction of the nozzle surface.