An irrigation device includes: a nozzle discharging liquid; a cover preventing the liquid discharged from the nozzle from splattering around the container; and a moving mechanism moving the cover between a first position and a second position. When moved to the first position, the cover covers space above the container. When moved to the second position, the cover is removed from the space above the container and the space is uncovered. The moving mechanism moves the cover (i) to the first position when the liquid is supplied to a plant, and (ii) to the second position when the supplying of the liquid to the plant ends.