To improve the accuracy of pattern to be formed and also to improve a throughput by a method in which a cathode, having specific work function, is controlled in a specific temperature range, and it is operated in a space charge limited region.

A cathode 1 consists of single crystal LaB6, and an electron discharging surface 1A of (310) orientation is formed. The work function of the electron discharging surface 1A is 2.65eV or smaller. The temperature of the cathode 1 is 1200 to 1400°C when single crystal 1aB is used. Besides, the work function of LaB6 is low on the (310) surface as 2.65eV. Pertaining to the operating condition of an electron gun, the sufficient electron emitting power from the cathode hardly receive statistical restriction under a space charge limited condition, because a current is limitted by the electric field in the vicinity of the cathode, and the electron gun has the lowest noise. As a result, a region where space charge is limited is used on a charged particle radiation lithography device.