The performance of freeze concentration at constant freezing rate (40 mm/h) with/without ultrasonic irradiation was examined using three one-component solutions containing only one solute (ionic or molecular concentration: 0.03 mol/L) and a three-component solution containing three solutes (each component concentration: 0.01 mol/L).Without ultrasonic irradiation, the solutes are hardly concentrated at this freezing rate.On the other hand, with ultrasonic irradiation, the concentration efficiency is very good.The solutes of larger molecular weight are concentrated more effectively than solutes of smaller molecular weight.On the contrary, the solutes of smaller molecular weight are concentrated more effectively than solutes of larger molecular weight and the capture ability corresponds well to the magnitude of the diffusion coefficient of each solute in the equal ionic or molecular concentration condition.The difference between the concentration efficiencies of each solute in the three-component solution is smaller than that between the concentration efficiencies in the one-component solution, but the order of the values of the efficiencies is the same.