Disclosed is an X-ray generator (1) comprised of an electron emission element (10) which receives energy to emit electrons; a metal piece (20) which receives the electrons emitted from the electron emission element (10) to emit an X-ray; and energy supply portions (3, 5) which supply energy to the electron emission element (10), wherein the energy supply portions (3, 5) irradiate a pyroelectric element functioning as an electron emission element with, for example, ultraviolet pulsed light, and a high-energy local portion is formed in the pyroelectric element. Thus, the X-ray generator wherein the size thereof can be reduced, and an on/off control for the generation of X-ray can be easily performed, can be provided.