PURPOSE: To obtain a flame retardant for thermosetting polymer giving a molded article having excellent surface characteristics in high operability, by introducing an ester bond segment into a specific polyoxyalkylene-halogenated bisphenol.

CONSTITUTION: A polyoxyalkylene-halogenated bisphenol expressed by formula (A is bivalent organic group such as methylene or ethylene; X is halogen; R is ethylene, propylene, etc.; m and n are ≥1) is produced by adding 4W6mol. of ethylene oxide or propylene oxide to 1mol. of bisphenol A. An ester-bond segment is introduced into the compound of formula either by reacting the compound with an organic dicarboxylic acid anhydride (e.g. phthalic anhydride or halogen-substituted aromatic dicarboxylic acid anhydride) or by reacting with an organic dicarboxylic acid anhydride and a 1,2-epoxide (e.g. ethylene oxide) in the presence of a catalyst.