A method of measuring the preload clearance in a double row rolling bearing. The method includes the steps of fixing the outer end face of the first inner ring in position while subjecting the outer end face of the second inner ring to a first load in a direction which moves the second inner ring toward the first inner ring at a relatively smaller constant amount so as not to reduce the preload clearance to zero, and obtaining a value H.sub.1 corresponding to the position of the outer end face of the second inner ring. Fixing the outer end face of the first inner ring in position while subjecting the outer end face of the second inner ring to a second load in a direction which moves the second inner ring toward the first inner ring at a relatively larger, constant amount enough to reduce the preload clearance to zero and obtaining the value H.sub.2 corresponding to the position of the outer end face of the second inner ring. Then calculating the difference between the value H.sub.1 and the value H.sub.2 thereby providing a displacement amount, and obtaining the preload clearance from the displacement amount based on a predetermined relationship between the displacement amount and the preload clearance.