In the presence of acetonitrile and NaOH, when H2O2 was added to the solution containing chlorophyll, it was found that a strong chemiluminescence (CL) was emitted. The blue light was emitted with the decomposition of chlorophyll. It is considered that the emitter contains the decomposition products of chlorophyll based on the following measurement results, such as the reduction of absorbance for chlorophyll and the difference of the spectral form between fluorescence and CL. The CL of the chlorines, such as chlorophyll, and the porphyrin analogue compounds were compared under the same conditions. Consequently, the obtained CL was strong in the chlorin complex which contains Mg or Zn. On the other hand, the CL was not strongly observed with porphyrin compounds. In the chlorophyll CL, when the chlorin ring is oxidized by the generated O-.(2)-, the excited molecule would be produced in the process of ring cleavage, and then CL is emitted to the outside.