Photoisomerization of alpha-(10 "-Cyanoanthracen-9 "-yl)ethyl spiro[cyclopropane-1,9’-fluorene]-2-carboxylates (CA-1 reversible arrow CA-2) in benzene has been studied by stepwise two-color two-photon excitation methods. The quantum yields of the T-1 depopulation by stepwise two-photon excitation and moreover those in the presence of naphthalene have been determined in addition to the photophysical parameters for both CA-1 and -2. Assuming some reasonable hypotheses, the detailed reaction mechanism has been established in comparison with the case of anthryl-substituted derivatives (An-1 and -2).