PURPOSE: To give enough strength to a check plate and to keep a good fixing condition by engaging the check plate fixed by a position adjusting means with a check plate engaging part provided at a roll neck fitting part on condition that the roll neck part is fitted into the roll neck fitting part.

CONSTITUTION: In a connecting structure, a roll neck part 4 of a rolling roll 3 is fitted into a roll neck fitting hole 2 provided on a coupling 1. The check plate 5 set by a pair of specified bolts 6 to the end face of the roll neck part 4 is engaged with a groove part 21 as a check plate engaging part provided on the roll neck fitting part 12. The check plate 5 is fixed by a forward bolt 7 and a backward bolt 8 as a position adjusting means. The other end part of the above coupling 1 is connected directly to the drive axis. Since the thickness of the check plate is made large to secure enough strength and engagement of the check plate to a check plate engaging part is carried out in surface contact, the bearing received by the check plate is reduced and prevented from damage. In this way, a good connecting condition can be kept for a long period of time.