PURPOSE: To enable uniform mixing continuously by providing a passage pipe arranged a cylindrical body having a catalytic action and forming plural blade bodies in the lengthwise direction of the cylindrical body.

CONSTITUTION: A noble metal as a simple substance such as platinium or an alkali metal salt, an alkaline earth metal salt, etc. is deposited on the elements 1W2. The element 1 and element 2 are arranged alternately and the end edges of those blades bodies 6, 8 are crossed rectangularly. The lengthwise direction of a reaction apparatus 15 is arranged to face a fluid source. By the arrangement, the fluid is passed through the passage partitioned by said blade bodies 6, 8 in the cylindrical bodies 5, 7 while being divided into two currents at the joined point of each element, and the reaction is accelerated by the catalytic action of each element.