In the present invention, a disposable tip or a tip of a cleaning system is attached to a lower edge section of a nozzle, and the nozzle detects a liquid level by receiving fluctuation of a light close to the disposable tip or to an opening section at a lower end of the tip in the cleaning system, for instance, a light reflected from the liquid surface. In the present invention, not only the liquid level is detected, but also a liquid is filled in the disposable tip or the tip of a cleaning system detachably attached to the nozzle, a light is passed through the liquid in the disposable tip or the tip of a cleaning system, and a change of a light amount of the sucked liquid is detected, so that, for instance, a suction rate of the liquid, transparency thereof, contaminated by bubbles therein, clogging and a state wherein water has been exhausted are determined.