A supporting shaft of a paper roll supports the paper roll and is supported by first to third supporting elements contacting internally an inner circumferential surface of a core cylinder of the paper roll at three circumferentially spaced points, as seen in a longitudinal direction of the core cylinder. A first supporting member provided with the first supporting element and a second supporting member provided with the second supporting element are fixed in opposition to each other by means of a short and small size core shafts or spindles provided at opposite longitudinal ends of the two supporting members. Since the shafts fixedly mounting the first and second supporting members are of small size, the paper roll supporting shaft can be reduced in weight, assembly can be improved, cost of production can be reduced.