To provide a method and an apparatus for evaluating frequency transmission characteristics through the engagement of gears, allowing the evaluation of the frequency transmission characteristics of gears using a motor and a vibration exciter of a real machine so that the vibration characteristics do not change.

The apparatus for evaluating gear frequency transmission characteristics, comprising a driven shaft to which a gear to be evaluated is attached, a drive shaft to which a drive gear engaging with the gear to be evaluated is attached, and rotation detectors which generate rotation signals for predetermined rotation angles and are attached to the driven shaft and the drive shaft, evaluates the frequency transmission characteristics of the gear to be evaluated through the difference in the signal outputs. The apparatus comprises translational excition means which minutely excites either the gear to be evaluated or the drive gear in the translational direction, rotational uneveness calculating means which determines the rotational transmission errors between the drive shaft and the driven shaft, and gear frequency transmission characteristics evaluating means which calculates the transmission characteristics from the relationship between the exciting force and the value of the rotational uneveness in the exciting frequency.