Providing an oxidation reactor a hydrocarbon can be oxidized efficiently even in energetically reactive. Oxidation reaction apparatus of the present invention includes a liquid introduction passage liquid containing hydrocarbons as the reaction substrate is introduced, and the gas introduction passage which the gas is introduced comprising oxygen and ozone, the liquid introduction channel a oxidation reactor having a gas-liquid mixing section for mixing the introduced liquid and the gas introduced from the gas introduction passage, and a flow reactor oxidation catalyst is fixed or filled from the flow reactor There it is composed of a fixed or packed oxidation catalyst monolithic carrier and the monolithic carrier, and / or the gas-liquid mixing section is characterized by a microbubble generator.