An error identification method of a machine tool includes an initial position measurement step of indexing a main spindle head rotation axis to an initial angle to measure an initial position of a measured jig, a table reference angle calculation step of calculating a reference angle of the table, a reference position measurement step of indexing the table rotation axis to the reference angle and indexing the main spindle head rotation axis to the initial angle, a relative position measurement step of respectively indexing the table rotation axis and the main spindle head rotation axis to a plurality of predetermined angles, an arc approximation step of approximating the plurality of measured position values into an arc, and an error calculation step of calculating an error of a center position of the rotation axis, a tilt error of the rotation axis, or a tilt error of the translational axis.