A transformer lifetime evaluation apparatus according to an embodiment comprises: a first storage part for storing insulation oil used for insulation of a transformer; a second storage part provided to be separated from the first storage part and storing insulation oil which is not used for the insulation of the transformer; a light-emitting unit for emitting light of a specified wavelength; a light-receiving unit for receiving light emitted from the light-emitting unit; a first optical cable connecting the light-emitting unit and the light-receiving unit, providing a moving path of light emitted from the light-emitting unit and received in the light-receiving unit, and disposed to extend through the first storage part; a second optical cable connecting the light-emitting unit and the light-receiving unit, providing a moving path of light emitted from the light-emitting unit and received in the light-receiving unit, and disposed to extend through the second storage part; and a calculation part connected to the light-receiving unit and receiving information about an optical property of methanol from the light-receiving unit.