A light irradiation device includes: at least one imaging means that images a monitoring region to continue to accurately irradiate a moving target with light； at least one projection means that irradiates the monitoring region with signal light； a control means that controls the imaging means to image the monitoring region and controls the projection means to emit the signal light； at least one propeller that moves the own device in the air； and a flight control means that controls flight of the own device by controlling the propeller, the control means controlling, when recognizing a light irradiation target to be irradiated with the signal light on image data imaged by the imaging means, the projection means to emit the signal light toward the light irradiation target.
