PURPOSE: To provide an analyzer which is small and simultaneously analyzes a wide range of mass and energy by deflecting charged particles by a magnetic field which has as a part of its boundary a circle of a circle arc having the center on the extension line in an incident direction of particles, and also deflecting them by an electric fields in the same direction or opposite direction, or right angle direction to the magnetic field.

CONSTITUTION: An analyzer is constructed with an electric field region 15 which applies an electric field E in a circle arc state to the surroundings of a magnetic field region 14, in a vertical direction to the flat surface of a container 11, and a particle detector 17 which detects particles deflected by energy mass of a charged particle beam after passing the magnetic field region 14 and the electric field region 15. The charged particle beam 16 entering from a beam introducing hole 12 is irradiated in an angle of θ=180° by a magnetic field B which has as a part of its boundary a circle or a circle arc having the center O on the extension line of an incident axis of the beam 16. Therefore, the magnification of a scale on the low energy side is almost free.