A polycarbonate copolymer includes: a repeating unit represented by a formula (1) below; and a repeating unit represented by a formula (2) below, in which the repeating unit represented by the formula (1) is formed from a bischloroformate oligomer having an average number of monomer units n represented by a formula (100) below in a range from 0.1 to 1.3. In the formulae (100) and (1), Ar1 represents a group represented by a formula (3) below. In the formula (2), Ar2 represents a divalent aromatic group. In the formula (3) below, X1 represents a single bond or an oxygen atom. R11 each independently represents a methyl group or an ethyl group.