With respect to an outer ring 2b in which a diameter DB1 of a first outer ring raceway 10c is greater than a diameter DB2 of a second outer ring raceway 10b (DB1>DB2), a method is realized which facilitates the entry of a grinding tool 12 into an inner side of the outer ring when these both outer ring raceways 10c and 10b are subjected to a grinding process.The grinding tool 12 is made to enter the inner side of the outer ring 2b through an opening on a side close to the first outer ring raceway 10c.