PURPOSE: To precisely conduct cleaning treatment to a sculpture or the like by supplying two sorts of jets to a mixing chamber of a mixing head at specified angles to each other to be mixed, atomizing a generated treatment jet, and forming a specified suction opening in a suction part for one jet.

CONSTITUTION: A mixing head 1 mixes supplied mixing media, and atomizes a treatment jet 50 generated from the mixing media. In the mixing head 1, a first jet containing liquid treating agent is introduced under pressure to a mixing chamber 30 from a suction part 12 through a first supply conduit 10. A second jet is introduced through a second supply conduit 20. An axis 22 of the second jet is inclined for a specified angle γ to an axis 11 of the first jet, and it is eccentrically extended. The suction part 12 has a suction opening so formed and/or oriented that the axis 22 of the second jet intersects the first jet. A sensitive and highly contoured surface can thus be precisely treated to be cleaned.