To prevent roller bearings from being disassembled when a shaft and a roll are separated in a roll unit, enabling reutilization of the roller bearings.

In a roll unit 2 mounted with the roll 4 on an outer periphery of the shaft 3 via roller bearings 5, there are provided, raceway grooves for positioning and arranging in an axial direction 9 groups of double row rollers on peripheral surfaces of inner races 7 comprised in the roller bearings 5, peripheral grooves 8a between the 9 groups of the double row rollers on peripheral surfaces of outer races 8 composed in the roller bearings 5, and retaining rings 10 for restraining the inner races 7 and the 9 groups of the rollers from moving away from the peripheral grooves 8a to both sides of an axial direction. Each of the retaining rings 10 has an anastatic letter-like sectional shape and is provided with an annular projection 11 engaging with the peripheral groove 8a and with annular projecting portions 12, 13 projecting to the both sides of the axial direction to abut against the peripheral surface of the outer race 8.