a spectral element configured to change a wavelength of light to be selected and configured to disperse light from a target object, and

an imaging element configured to receive light dispersed into a plurality of wavelengths by the spectral element to acquire a plurality of spectral images, the spectrometry method comprising:

(a) identifying a common feature between a first spectral image and a second spectral image other than the first spectral image of the plurality of spectral images acquired by the imaging element;

(b) detecting a relative position shift amount between the first spectral image and the second spectral image; and

(c) aligning the first spectral image and the second spectral image based on the relative position shift amount being detected, wherein

the alignment of (c) includes correcting a position of the second spectral image with respect to a position of the first spectral image based on the common feature, and

an interval between a center wavelength of a first transmission peak of light corresponding to the first spectral image and a center wavelength of a second transmission peak of light corresponding to the second spectral image is no more than twice a first full width at half maximum of the first transmission peak or a second full width at half maximum of the second transmission peak.