A method of regenerating an exhaust gas treatment catalyst having ash adhering to a surface thereof, the method comprising: a used catalyst crushing step (S1) of crushing the exhaust gas treatment catalyst that has been used and comprising titanium oxide as a main component and further tungsten oxide and vanadium oxide; a separating step (S2) of separating the crushed exhaust gas treatment catalyst into coarse pieces having a size exceeding a threshold size S and fine particles having a size not larger than the threshold size S, the threshold size S having a value not smaller than 0.105 mm; a used catalyst pulverizing step (S3) of pulverizing the separated coarse pieces into a fine powder having an average particle diameter not larger than 0.1 mm; a molding step (S5) of molding the pulverized fine powder as a raw material into a molded precursor of an exhaust gas treatment catalyst; a precursor calcining step (S7) of calcining the molded precursor of the exhaust gas treatment catalyst, thereby obtaining a base ; the method being characterized in that it comprises: a newly-made catalyst crushing step (S8) of crushing an exhaust gas treatment catalyst that has been newly made; a slurrying step (S9) of slurrying the crushed newly-made exhaust gas treatment catalyst, thereby obtaining a slurry liquid ; a slurry coating step (S10) of coating a surface of the base obtained by the calcination in the precursor calcining step (S7) with the slurry liquid ; and a coating calcining step (S12) of calcining the base coated with the slurry liquid at a higher temperature, between 525°C and 700°C, than a calcination temperature during production of the crushed newly-made exhaust gas treatment catalyst . a used catalyst crushing step (S1) of crushing the exhaust gas treatment catalyst that has been used and comprising titanium oxide as a main component and further tungsten oxide and vanadium oxide; a separating step (S2) of separating the crushed exhaust gas treatment catalyst into coarse pieces having a size exceeding a threshold size S and fine particles having a size not larger than the threshold size S, the threshold size S having a value not smaller than 0.105 mm; a used catalyst pulverizing step (S3) of pulverizing the separated coarse pieces into a fine powder having an average particle diameter not larger than 0.1 mm; a molding step (S5) of molding the pulverized fine powder as a raw material into a molded precursor of an exhaust gas treatment catalyst; a precursor calcining step (S7) of calcining the molded precursor of the exhaust gas treatment catalyst, thereby obtaining a base ; the method being characterized in that it comprises: a newly-made catalyst crushing step (S8) of crushing an exhaust gas treatment catalyst that has been newly made; a slurrying step (S9) of slurrying the crushed newly-made exhaust gas treatment catalyst, thereby obtaining a slurry liquid ; a slurry coating step (S10) of coating a surface of the base obtained by the calcination in the precursor calcining step (S7) with the slurry liquid ; and a coating calcining step (S12) of calcining the base coated with the slurry liquid at a higher temperature, between 525°C and 700°C, than a calcination temperature during production of the crushed newly-made exhaust gas treatment catalyst . a newly-made catalyst crushing step (S8) of crushing an exhaust gas treatment catalyst that has been newly made; a slurrying step (S9) of slurrying the crushed newly-made exhaust gas treatment catalyst, thereby obtaining a slurry liquid ; a slurry coating step (S10) of coating a surface of the base obtained by the calcination in the precursor calcining step (S7) with the slurry liquid ; and a coating calcining step (S12) of calcining the base coated with the slurry liquid at a higher temperature, between 525°C and 700°C, than a calcination temperature during production of the crushed newly-made exhaust gas treatment catalyst . <EOS>