which will be described later according to an embodiment of the present invention the vibration unit 300 is disposed for the water stored in the water reservoir 210 and performs a function of creating an oscillation in the water to atomize it the vibration unit 300 may include a lower part 310 and an upper part 320 the lower part 310 can include or accommodate the vibrator 312 of fig3 for vibrating the water and the upper part 320 is coupled to the second hinge part 130 to suspend the vibration unit 300 to float on the water as a whole while supporting the lower part 310 meanwhile the vibration unit 300 especially the lower part 310 may further include a water level sensor not shown to inform the user about whether the water is required to be replenished by detecting water at a predetermined location the water level sensor can provide a prescribed electric signal to the above described electric circuit to perform a function of start and stop the vibration of the vibrator 312 that is a control function that starts the vibration of the vibrator 312 if water is detected and stops the vibration of the vibrator 312 if water is not detected may be performed in the following a coupling state of the upper body 100 and the upper part 320 of the vibration unit 300 is described referring to fig1 and 2 in fig1 the arrow indicates a flowing route of the external air incoming via the fan 110 fig2 is a schematic diagram showing a coupling state of the upper body and the upper part of the vibration unit according to an embodiment of the present invention.