PURPOSE: To progress reaction rapidly by leading liquid drops and gas into alternating electric fields and giving deforming vibrations to the liquid drops at the time of causing contact reaction of the liquid drops and gas.

CONSTITUTION: A gas is flowed in a duct 1, and liquid is sprayed into said duct 1 from a nozzle 2 so that the liquid is separated as fine liquid droplets in the gas. When alternating electric fields are applied to the gas contg. such liquid droplets in an alternating electric field zone provided with electrodes 3, 4, the liquid droplets make deforming vibrations. Hence, the uniformalization of the concn. of the prodduct of reaction and the materials to be reacted in the liquid droplets is accelerated and the reaction of the liquid droplets and gas progresses rapidly.