To provide a roll cassette device which can support a plurality of types of fillet rolling machining with different journal width in fillet rolling machining of a journal part in a crank shaft.

A right and left pair of fillet rollers 25a and 25b is housed and arranged in right and left front cages 23a and 23b attached a case 15 and a roller holding groove 29 of a rear cage and its attitude can be changed within the range of an angle θ with a fulcrum Q as the center. The cages 23a and 23b can approach to and leave from each other. When this roll cassette device 1 is pressed onto the journal part J, the cages 23a and 23b approach to or leave from each other with the fillet rollers 25a and 25b, and an angel β between the fillet rollers 25a and 25b is changed according to the span of fillet parts F and F.