Micropores penetrating a vibration plate 12 in a thickness direction thereof are formed, in which the vibration plate 12 atomizes a solution by vibration of a piezoelectric vibrator 11 that generates ultrasonic vibration when current is applied thereto. In addition, the spraying time and the spraying interval time are controlled by turning on or off the current applied to the piezoelectric vibrator 11, such that a value of [50% particle diameter of spray particles in cumulative volume distribution]×([spraying time]/[spraying interval time]) becomes 0.2 to 2.5 μm.