A process for producing a polycarbonate through transesterification in a molten state, wherein both a phosphorus-bearing basic compound and a quaternary phosphonium salt having a specific structure are used as the polymerization catalyst; and processes for producing a polycarbonate by preparing a polycarbonate prepolymer by preliminary polymerization and subjecting the prepolymer to main polymerization in a solid or swollen solid state, wherein (1) both a phosphorus-bearing basic compound and a quaternary phosphonium salt having a specific structure are used as the polymerization catalyst in both the preliminary polymerization and the main polymerization; (2) a phosphorus (III or V) compound or a nitrogenous organic basic compound is used in the main polymerization as the polymerization catalyst; or (3) the main polymerization is conducted in such a state that the oxygen content of the gas phase is 2 ppm or below. These processes enable extremely efficient production of a high-quality polycarbonate excellent in appearance and the resistances to heat and hydrolysis.
