PURPOSE: To measure the balance of a rotating body accurately in a shorter measuring time by detecting the lateral oscillations of said body, and ejecting marking materials or weight materials for correcting balance thereby marking the unbalance positions directly or correcting the balance thereof.

CONSTITUTION: A rotating body R is pivotally supported by means of Y-shaped supporting rods 1', 2' of a pair of lateral oscillation detectors 1, 2, and is revolved at high speeds with a pulley 4 and a belt 5. The lateral oscillation signals from the detectors 1, 2 are inputted to an arithmetic circuit 6, from which the signals corresponding respectively to only the quantities of the unbalance on one side and other end side of the body R are drawn out. Said signals are transmitted through tracking filters 7, 8 and are stored in storage devices 9, 10; at the same time, pulse generators 11, 12 are driven by said signals, whereby the synchronizing pulses for the unbalancing positions are outputted. Control circuits 15, 16 drive injectors 13, 14 to stick marking materials accurately on the unbalancing positions upon lapse of a constant time after the generation of the synchronizing pulses of the generators 11, 12.