A laser peening device includes: a laser oscillator; an irradiation nozzle for irradiating a laser beam onto an irradiation target; an optical transmission unit; a shutter attached to the optical transmission unit; a liquid feeder for supplying the irradiation nozzle with liquid to cause the liquid to flow along an optical path of the laser beam running from the irradiation nozzle to the irradiation target; an ongoing irradiation sensor for obtaining information on ongoing laser beam irradiation indicating whether the laser beam is being appropriately irradiated for execution of ongoing laser peening operation on the irradiation target; and a control unit controlling the shutter according to the information on the ongoing laser beam irradiation obtained by the ongoing irradiation sensor.