A spirobenzothiapyran derivative bearing a monoaza-12-crown-4 moiety shows remarkable stabilization of its photoinduced colored isomer (merocyanine form) by complexation of a metal ion, especially Li+and Ag+. Comparison of the crowned spirobenzothiapyran with its corresponding spirobenzopyran derivative indicates that the stabilization of the merocyanine form in the presence of Li+and Ag+are derived mainly from the metal-ion complexing ability of its crown ether moiety and the metal-ion affinity of its merocyanine thiophenolate anion, respectively.