The droplet diameter distribution and concentration characteristics in ultrasonic atomization were experimentally studied. The samples were aqueous solutions of methanol, ethanol and 1-propanol. The diameter distribution of atomized droplet showed the normal one, and the median diameter and standard deviation were expressed by means of the ultrasonic condition and the liquid properties. The concentration characteristic in ultrasonic atomization was analyzed by using the model of shell and core of the atomized droplet, where the former and latter consist of solute and solution, respectively. The surface solute amount in droplet multiplied by the molecular volume increased with increasing content of solute in bulk liquid and was independent of alcohol kinds. The liquid flow rate and the solute molar fraction in accompanied liquid were estimated from the diameter distribution and the surface solute amount.