A transformer noise performance diagnosis method comprising: a first step (S1) of measuring an excitation noise of a stacked iron core included in a transformer and acquiring a frequency spectrum of the excitation noise, the stacked iron core being formed by stacking electrical steel sheets; a second step (S2) of, for excitation vibration calculation for the stacked iron core in the transformer using a constitutive equation that includes an elasticity matrix representing a relationship between stress and strain in the stacked iron core in matrix representation, determining transverse elasticity moduli in two planes each including a stacking direction of the stacked iron core in the transformer, the transverse elasticity moduli being included as elements in the elasticity matrix; a third step (S3, S4, S5) of performing the excitation vibration calculation for the stacked iron core in the transformer using the constitutive equation that includes the elasticity matrix including, as the elements, the transverse elasticity moduli determined in the second step and acquiring a frequency spectrum of an excitation vibration of the stacked iron core in the transformer; a fourth step (S6) of calculating a difference between the frequency spectrum of the excitation noise of the stacked iron core in the transformer acquired in the first step and the frequency spectrum of the excitation vibration of the stacked iron core in the transformer acquired in the third step, as a difference spectrum; and a fifth step (S7) of diagnosing noise performance of the transformer based on the difference spectrum calculated in the fourth step. a first step (S1) of measuring an excitation noise of a stacked iron core included in a transformer and acquiring a frequency spectrum of the excitation noise, the stacked iron core being formed by stacking electrical steel sheets; a second step (S2) of, for excitation vibration calculation for the stacked iron core in the transformer using a constitutive equation that includes an elasticity matrix representing a relationship between stress and strain in the stacked iron core in matrix representation, determining transverse elasticity moduli in two planes each including a stacking direction of the stacked iron core in the transformer, the transverse elasticity moduli being included as elements in the elasticity matrix; a third step (S3, S4, S5) of performing the excitation vibration calculation for the stacked iron core in the transformer using the constitutive equation that includes the elasticity matrix including, as the elements, the transverse elasticity moduli determined in the second step and acquiring a frequency spectrum of an excitation vibration of the stacked iron core in the transformer; a fourth step (S6) of calculating a difference between the frequency spectrum of the excitation noise of the stacked iron core in the transformer acquired in the first step and the frequency spectrum of the excitation vibration of the stacked iron core in the transformer acquired in the third step, as a difference spectrum; and a fifth step (S7) of diagnosing noise performance of the transformer based on the difference spectrum calculated in the fourth step. <EOS>