Chemically induced dynamic electron polarization (CIDEP) generated through the interaction between the lowest excited singlet oxygen molecule and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) radical was observed by the time-resolved ESR technique. Excited singlet oxygen molecules were produced by the triplet sensitizer through energy transfer. Absorptive electron spin polarization was generated on the free radical in the excited singlet oxygen molecule - free radical system, in which the CIDEP generation was interpreted by the radical-triplet pair mechanism with doublet precursor (DP-RTPM). The CIDEP time profile was successfully analyzed by using the Bloch equations. Quenching of 1 O 2 by β-carotene provides further evidence for DP-RTPM in the 1 O 2 -TEMPO system.