A method for manufacturing a semiconductor device for detecting a physical amount distribution, the semiconductor device comprising unit components arrayed in a predetermined order, the unit components each including a unit signal generation portion for detecting an electromagnetic wave and outputting the corresponding unit signal. A diffraction grating is provided on the incident light side of a spectral image sensor, the diffraction grating including scatterers, slits, and scatterers 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 in each photodiode group.