PURPOSE: To accelerate oxidation reaction by projecting ultrasonic waves and/or UV rays to a material to be treated while bringing ozone into dispersive contact or contact with said material, thereby cracking the ozone and generating excitation oxygen atoms.

CONSTITUTION: The ultrasonic waves and/or UV rays are projected to the material to be treated while the ozone is brought into dispersive contact or contact therewith. For example, water 1 to be treated is fed through an ozone flow 3 and suction pipe part 4 from an ejector part 2 to a treatment tan 5. The ozone is dispersed into the water to be treated by the air flow dispersing and mixing effect of the ejector 2 and the ultrasonic effect, etc., to be described afterward in said pipe part 4. Furthermore, the dispersion of the ozone is accelerated by the ultrasonic waves from an ultrasonic oscillator 6 in the pipe part 4. The ozone, irradiated with the UV rays from a UV lamp 7, generates the excitation oxygen atoms, etc., to accelerate the reaction with the treated water. As a result, the decoloration, deodorization, sterilization or oxidation, etc., of the water to be treated by the ozone are efficiently executed.