To produce a resin excellent in moldability, heat stability, mold- corrosion resistance, etc., and useful for a formed article having a low birefringence such as an optical material by polymerizing specific two kinds of divalent phenols with a carbonic acid diester in molten state.

(A) An aromatic dihydroxy component whose at least 80mol% is (i) 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and (ii) 2,-2bis(3-methyl-4- hydroxyphenyl)propane, wherein a ratio of the components (i) to (ii) is 99:1 to 20:80, preferably 80:20 to 20:80 in terms of molar ratio is polymerized with (B) a carbonic acid diester (preferably, diphenyl carbonate) in molten state. The melt polymerization is preferably carried out in the presence of a polymerization catalyst consisting of an alkali metal or alkaline earth metal compound and a nitrogen-containing basic compound.