ANALYZER

An analyzer according to the present invention includes an electron emission element, a detector, an electric field generator, an electrostatic gate electrode, and a controller, in which the electron emission element includes a lower electrode, a surface electrode, and an intermediate layer, and directly or indirectly generates anions by electrons emitted in an ionization region between the electron emission element and the electrostatic gate electrode, the electrostatic gate electrode controls injection of the anions into a drift region between the electrostatic gate electrode and the detector, the detector detects the anions move through the drift region by a potential gradient, and the controller applies a pulse voltage between the lower electrode and the surface electrode, and applies a voltage to the electrostatic gate electrode such that the electrostatic gate electrode injects the anions into the drift region during a time when the pulse voltage is on.