A magnetron comprising: a yoke that defines an accommodating space and has a yoke opening at a first portion of the yoke; a first magnet located in the accommodating space and having a first side coupled to an inner surface of the first portion of the yoke; a first pole piece that has a funnel shape and that is located at a second side of the first magnet, the second side being opposite to the first side; a fifth-harmonic-frequency choke configured to block a fifth harmonic frequency from an electromagnetic wave, the fifth-harmonic-frequency choke being located in the yoke opening; a third-harmonic-frequency choke configured to block a third harmonic frequency from the electromagnetic wave; a ceramic part configured to output the electromagnetic wave including a plurality of frequencies and being arranged outside the accommodating space adjacent to the yoke opening; and a second-harmonic-frequency choke configured to block a second harmonic frequency from the electromagnetic wave, the second-harmonic-frequency choke extending along a center line of the magnetron; wherein: the third-harmonic-frequency choke (330, 336) is configured to block a third bandwidth of frequency; the fifth-harmonic-frequency choke is configured to block a fifth bandwidth of frequency that is greater than the third bandwidth; and the second-harmonic-frequency choke is configured to block a second bandwidth of frequency that is greater than the fifth bandwidth. a yoke that defines an accommodating space and has a yoke opening at a first portion of the yoke; a first magnet located in the accommodating space and having a first side coupled to an inner surface of the first portion of the yoke; a first pole piece that has a funnel shape and that is located at a second side of the first magnet, the second side being opposite to the first side; a fifth-harmonic-frequency choke configured to block a fifth harmonic frequency from an electromagnetic wave, the fifth-harmonic-frequency choke being located in the yoke opening; a third-harmonic-frequency choke configured to block a third harmonic frequency from the electromagnetic wave; a ceramic part configured to output the electromagnetic wave including a plurality of frequencies and being arranged outside the accommodating space adjacent to the yoke opening; and a second-harmonic-frequency choke configured to block a second harmonic frequency from the electromagnetic wave, the second-harmonic-frequency choke extending along a center line of the magnetron; wherein: the third-harmonic-frequency choke (330, 336) is configured to block a third bandwidth of frequency; the fifth-harmonic-frequency choke is configured to block a fifth bandwidth of frequency that is greater than the third bandwidth; and the second-harmonic-frequency choke is configured to block a second bandwidth of frequency that is greater than the fifth bandwidth. the third-harmonic-frequency choke (330, 336) is configured to block a third bandwidth of frequency; the fifth-harmonic-frequency choke is configured to block a fifth bandwidth of frequency that is greater than the third bandwidth; and the second-harmonic-frequency choke is configured to block a second bandwidth of frequency that is greater than the fifth bandwidth.