a plurality of substrate holders arranged in a left-right direction and each configured to hold a substrate;

a first nozzle provided to be shared by the plurality of substrate holders and configured to discharge a first processing liquid to the substrate at a first discharge position on the substrate held by each of the plurality of substrate holders;

a first arm supporting the first nozzle and configured to move the first nozzle in a plan view between a first standby area, which is outside a region in which the substrate is held by each of the plurality of substrate holders in a plan view, and the first discharge position;

a first illumination provided on a distal end side of the first arm and configured to move with the first nozzle and to irradiate the first nozzle with light; and

a camera provided on the distal end side of the first arm and configured to move with the first nozzle and to capture an image of the first nozzle irradiated with the light from the first illumination,

wherein the first illumination is configured to emit the light obliquely downward toward a base end side of the first arm.