We achieved capillary electrophoresis with chemiluminescence detector using on-capillary detection, taking advantage of the commercially available chemiluminescence reagent (LUMICA) and its oxidant. A mixture of dansyl tryptophan and dansyl glycine as a model sample migrated in two different running buffers, both containing LUMICA and the oxidant, indicating chemiluminescence was generated by the reaction of LUMICA, the oxidant, and dansyl alpha-amino acids. When the alpha-amino acids went through the detection window on the capillary, the chemiluminescence signals were observed with the chemiluminescence detector using on-capillary detection. This new concept of on-capillary chemiluminescence detection did not require any interface device between the electrophoresis capillary and the chemiluminescence detector.