To obtain a flame retardant exhibiting an excellent flame retardant effect and besides being less problematic in environmental pollution by reacting bisphenol A with diphenyl carbonate and a phosphoric ester having a specified structure.

This compound is obtained by reacting bisphenol A with diphenyl carbonate and a phosphoric ester represented by formula I under heating and agitation in the presence of a transesterification catalyst such as a basic compound. The compound is desirably one having a molecular structure comprising structural units represented by formula II and being structural units of a polycarbonate and phosphate-containing structural units represented by formula III and having a weight-average molecular weight of 2,000-30,000. It is useful as a flame retardant added to a polycarbonate, a polyolefin, a polyester, a styrene polymer or an acrylic polymer. In the formulae, R1 to R6, R9 and R10 are each hydrogen or methyl; m is 0 or a positive integer; and n2 and n3 are each a positive integer.