Provided is a method of culturing green algae which promotes the growth of the green algae which is in a state of being a green swarm cell by irradiating the green algae that accumulate astaxanthin with an artificial light. The green algae are grown in a liquid medium while maintaining a state in which the color of a culture solution of the green algae is green or brown by alternately and continuously radiating a red illumination light and a blue illumination light.