Low-temperature C-13 NMR and IR spectra of the metastable photomerocyanine (PMC) of spirophenanthrooxazine (SPO) show that PMC is in quinoidal structure. Especially, C-13 NMR study directly evidences the formation of two quinoidal PMCs in CD2Cl2 upon UV irradiation. The quantum chemical study of SPO shows that among open forms TTC and CTC are more stable than TTT and CTT because of the formation of the intramolecular hydrogen bond.