Provided is a polycarbonate-polyorganosiloxane copolymer having high impact resistance and excellent transparency, in particular, a high total light transmittance and a small haze, and a method of producing thereof. Specifically, provided is a polycarbonate-polyorganosiloxane copolymer, containing a main chain having a repeating unit represented by the following general formula (I) and a constituent unit represented by the following general formula (II), in which: n in the general formula (II) is 25 to 50; and the copolymer satisfies the following conditions (a) and (b): (a) a molded article having a thickness of 2 mm made of the copolymer has a total light transmittance measured based on ISO 13468 of 88% or more and a haze measured based on ISO 14782 of 0.7% or less; and (b) a molded article having a thickness of 3 mm made of the copolymer has a total light transmittance measured based on ISO 13468 of 88% or more and a haze measured based on ISO 14782 of 1.0% or less.(In the formulae, R1 and R2 each independently represent a halogen atom, an alkyl group or an alkoxy group, X represents a single bond, an alkylene group, an alkylidene group, a cycloalkylene group, a cycloalkylidene group, —S—, —SO—, —SO2—, —O— or —CO—, and a and b each independently represent an integer of 0 to 4. R3 to R6 each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or an aryl group, Y represents a single bond, or an organic residue containing an aliphatic or aromatic moiety, and n represents an average repetition number.)