To efficiently detect the light to be emitted in a chemical light emission reaction to be started by mixing a chemical luminescent reagent, etc., by using a flow cell reactor in which a filler of a fixed catalyst substance is filled in a flow cell.

A chemical luminescent reagent is excited through co-existence of the chemical luminescent reagent, an oxidant and a catalyst substance to excite the chemical luminescent reagent in a chemical emissive condition when in co-existence therewith. A chemical emission detector 30 determines the oxidant by the intensity of the light emitted from the excited chemical luminescent reagent. A flow cell reactor in which a filler of the fixed catalyst substance is filled in a flow cell is used, and the emission from the flow cell reactor part is detected. This chemical emission detection system comprises solution tanks 25, 27, solution feed pumps 26, 28, a sample pouring part 29, a chemical emission detector 30, a recorder 31 and a waste solution tank 32. The flow cell reactor is stored in a box to form the chemical emission detector 30.