A phosphorus-containing hydroquinone derivative represented by a general formula (1): ##STR00001## (where R.sup.1 and R.sup.2 represent linear or branched alkyl groups that are identical or may be different, and/or R.sup.1 and R.sup.2 may form a circular group; X represents an oxygen atom or sulfur atom; Y and Z represent hydrogen atom, hydroxy group, linear or branched alkyl group, aralkyl group, alkoxy group, allyl group, aryl group or cyano group, and/or Y and Z may form a circular group). The present invention provides phosphorus-containing hydroquinone derivatives that are useful for intermediate materials for reactive type flame-retardant agents or phosphorus-containing epoxy resins.