A head unit to be detachably arrayed in a predetermined array direction on a base member includes: an ink discharge head having a nozzle surface configured to discharge an ink; a head holder attachable to and detachable from the base member while holding the ink discharge head in a holding region; and a posture adjustment mechanism configured to adjust a posture of the nozzle surface with respect to the head holder by rotating the ink discharge head with respect to the head holder about an axis of rotation perpendicular to both a surface normal to the nozzle surface and the array direction in a state where the head holder is not attached to the base member.