A device for determining a target generation condition for a target generator which is driven by a pulse voltage to generate a droplet of a target material may include a detector configured to detect a target generated by the target generator and output a detection signal of the target, and a controller configured to control a pulse duration of the pulse voltage for driving the target generator. The controller can determine whether or not a target is generated by the target generator based on the detection signal, and determine whether or not the generated target includes a plurality of droplets based on the detection signal.