A bisphenol compound represented by the following general formula: ##STR1## where R is an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 1 to 5 carbon atoms, a perfluoroalkylene group having 1 to 5 carbon atoms, a perfluoroalkylidene group having 1 to 5 carbon atoms, a SO.sub.2 group or an O group; and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are the same or different alkyl groups, alkenyl groups, aryl groups, alkylaryl groups or aralkyl groups, each having 1 to 25 carbon atoms, can give vulcanization products having a good resistance to hot water, when used as a cross-linking agent for terpolymers of tetrafluoroethylene/perfluoro (alkyl vinyl ether)/ethylenically unsaturated cure site monomer.