To provide a locking tool used for a delivering device of a roll which is capable of preventing the movement of the roll from the fixed position even when the rotation, the stop and the re-rotation of the roll are rapidly and intermittently repeated during the packaging work, and easily changing the used roll, and a roll holding structure capable of consistently delivering the sheet by using the locking tool.

A roll holding device 1 includes a holding body 2 which has a hollow cylindrical fitting body 21, a shaft body 220 inserted in the fitting body 21 and an expansion/contraction mechanism 3 provided on the fitting body 21 to fix a roll, and is inserted in the roll 9, and a locking tool 4 having a flexible projecting part 412 with its diameter being gradually decreased toward an end of the holding body 2, a fastening nut 41 having grooves or gaps of the required number at the predetermined spacing toward the axial direction therebetween, and a pressing nut 42 with its diameter being gradually increased toward the projecting part 412, and having a pressing unit attached to an outer surface of the projecting part 412 and pressing it.