PURPOSE:To surely position a chock built-in roll to a roll supporting base by arranging a pair of chock supporting members on a chock attaching and detaching device and extending this supporting member in the roll axial direction upto the chock of the roll both ends. CONSTITUTION:A pair of chock supporting members 5 are provided on a roll supporting base 4 and extended for long in the roll axial direction upto the chock of the roll both ends. The member 5 is made so that the positions in the height direction, the right and left directions become the same as those of the truck rail 12 provided on a roll changing truck 11 and a wheel 7 and hook 15 are provided on the chock 2. A chock built-in roll 1 is placed on the truck 11 in this state, passed through the above of the chock supporting member 5 by advancing a push puller 13 and hooks 14, 15 are linked each other. The chock built-in roll 1 is stopped at the prescribed position of the above of the roll supporting base by retreating the push puller 13. The linking of both hooks 14, 15 are released, the chock built-in roll is placed on the roll supporting base 4 by ascending a lift device 6 and the roll 1 and chock 2 are separated.