A correction method for an optical mechanism having an optical member and a fixed portion is provided, including: an external apparatus measures the angle between the optical axis of the optical member and a reference surface of the fixed portion; the result of measuring the angle between the optical axis and the reference surface is compiled into data; the data is input into a control module; the control module transmits a signal to a driving module according to the data; and the driving module drives the optical member to rotate or move relative to the fixed portion upon receiving the signal. The optical mechanism does not include a sensor to detect the angle between the optical axis and the reference surface.