Reaction detection method to detect a chemical reaction with respect to a target substance, for instance, glucose (5) in a sample (32) includes the steps of forming a reaction layer (3) to induce the chemical reaction and forming an oxygen transfer layer (2), which has an oxygen transmission rate higher than that of the reaction layer (3) and which transfers oxygen (4) in the air (1) to the reaction layer (3), between the reaction layer (3) and the air (1), where the oxygen is consumed in the chemical reaction. Chemical reaction rate with respect to target substances in a sample is increased.