The present invention provides an ion-exchange resin catalyst, as a catalyst for preparing bisphenol from phenol compounds and ketone, which has a higher selectivity to bisphenol and a longer life time, as compared to a conventional ion-exchange resin, and a method for preparing the same.The present invention also provides a method for preparing bisphenol comprising reacting phenol compounds with ketone, wherein the modified acidic ion-exchange resin in which at least one kind of cationic compound selected from the following (a), (b), (c) and (d) ionically binds to an acidic functional group, is used as a catalyst: (a) a quaternary phosphonium ion, (b) a quaternary ammonium ion, (c) a bis(phosphoranylidene) ammonium ion, and (d) an N-substituted nitrogen-containing aromatic cation.