A new cationic surfactant, 1,1,2,2-tetrahydroheptadecafluorodecylpyridium chloride (HFDePC), quenches the fluorescence emission from pyrene in pure micelles but hardly quenches it in mixed micelles composed of fluorocarbon and hydrocarbon surfactants. Pyrene is located in hydrocarbon-rich micelles, and its fluorescence is quenched by cetylpyridinium chloride. However, HFDePC is mainly solubilized in fluorocarbon-rich micelles, and a collision probability between pyrene and HFDePC would be small within the lifetime of the excited pyrene. That is, the depression of quenching by HFDePC could be ascribed to the coexistence of two kinds of mixed micelles. The effects of addition of salt and temperature toward the depression of quenching were also examined.