To provide an active type thin film cold cathode which is capable of extracting a large current even at a low voltage, and its manufacturing method.

This cold cathode has layers on a Si substrate 1 formed from bottom to top in the following order: a boron nitride film 2, a SiO2 layer 3 and a metal thin film 4. Opening parts are formed in the SiO2 layer 3 and a metal thin film 4, where the boron nitride film 2 is exposed. The metal thin film 4 is grounded and a negative voltage is applied to the Si substrate 1 or the boron nitride film 2. A large electric field is generated in the SiO2 layer 3 even by a small potential difference because of its small thickness, therefore, electrons 6 are emitted from the boron nitride film 2. The emitted electrons reach an anode 5 by accelerated with a potential field applied between the metal thin film 4 and the anode 5.