Process for producing bisphenol A

The present invention provides a process for producing bisphenol A which is capable of prolonging the life of an acid-type ion exchange resin partially modified with a sulfur-containing amine compound as catalyst, and increasing the yield of bisphenol A per unit quantity of the catalyst. There is disclosed a process for producing bisphenol A by reacting acetone with phenol in the presence of an acid-type ion exchange resin partially modified with a sulfur-containing amine compound as catalyst and alkylmercaptan as co-catalyst, said process comprising: conducting said reaction using a multi-stage reaction apparatus comprising at least two individual reactors connected in series to each other, wherein the molar ratio of total alkylmercaptan to total acetone and the molar ratio of total acetone to phenol are increased as the conversion rate of the phenol is decreased.