The present invention provides a device and a method for image reconstruction at different X-ray energies that make it possible to achieve image reconstruction with higher accuracy. A device for image reconstruction at different X-ray energies includes: an X-ray source 1 that irradiates a specimen to be imaged 2 with X-rays; an energy-dispersive detector 4 that detects a characteristic X-ray emitted from the specimen to be imaged 2; a signal processing means that quantifies the peak of the characteristic X-ray detected by the detector 4; and an image reconstruction means that reconstructs an image on the basis of a signal from the signal processing means.