PURPOSE: To reduce treating time and to improve concentration efficiency by vaporizing and concentrating a liq. soln. atomized in an ultrasonic atomizer with a carrier air current in the concentrator main body and allowing water to flow down on the inner wall surface of the main body from a water injection pipe.

CONSTITUTION: The ultrasonic atomizer 4 is fixed on the top of the concentrator main body 1 capable of forming a carrier air current. A vacuum pump 5 is connected to the bottom of the main body 1, and the water injection pump 11 is connected to the top of the main body 1. The liq. soln. atomized in the atomizer 2 is vaporized and concentrated by phe carrier air current in the main body 1, and water is allowed to flow down on the inner wall surface of the main body 1 from the water injection pipe 11. Consequently, a special high-pressure air conveyor is not needed, mist is not deposited on the well surface of the concentrator, treating time is reduced, and concentration efficiency is improved.