A magnetron which generates a high-frequency energy in the Terahertz band is provided. The magnetron includes a cathode unit, which is connected to a terminal of a power source, and which selectively emits an electron according to when power is supplied; an anode block, which is connected to another terminal of the power source, and which has an operation chamber in which the emitted electron moves; and one or more resonance cavities which generate a high-frequency energy by a movement of the emitted electron; and a pair of magnet units forming a magnetic field in the operation chamber.