The present invention related to an ultrasonic nebulizer apparatus and a method for adjusting an operation frequency and checking an operating state of the ultrasonic nebulizer apparatus. The apparatus according to the present invention comprises a current detecting element for actively detecting an electrical current passed through it early. By detecting the current to determine a resonance frequency and whether deviated from a predetermined normal range, the nebulizer apparatus according to the present invention can check the operating state and operate at the resonance frequency for increasing efficiency and saving power.