To enable an imaging apparatus to achieve high resolution and sufficient color reproducibility.A diffraction grating 1 is provided on the incident light side of a spectral image sensor 10, the diffraction grating 1 including scatterers such as scatterers 3, slits 5, and scatterers 7 which are disposed in that order. An electromagnetic wave is scattered by the scatterers to produce diffracted waves, and by using the fact that interference patterns between the diffracted waves change with wavelengths, signals are detected for respective wavelengths by photoelectric conversion elements 12B, 12G, and 12R in each photodiode group 12.