Abstract: Measurement is made of centrifugal force produced on a crankshaft to be tested that is being rotated about its rotation axis, to provide centrifugal force variation information of the crankshaft. Also, measurement is made of errors in respective rotational phases of crankpins of the crankshaft about rotation axes of the crankpins. Dummy information, comprising rotational unbalance data representative of rotational unbalance components to be removed from the centrifugal force variation information of the crankshaft, is created using the measured errors in the respective rotational phases. Then, an initial rotational unbalance value of the crankshaft is determined, using the dummy information and the centrifugal force variation information of the crankshaft.