To provide a magnetron having stable characteristics by securely brazing strap rings to vanes without much increasing the accuracy of the parts of the strap rings.

In a magnetron having at least a plurality of vanes 102 provided radially inside an anode cylinder 103, a pair of strap rings 161, 162 to which every other vane 102 is electrically connected to provide the same potential, and an antenna lead 107 connected to one of the vanes 102 to serve as a microwave output guide, first layers 12 of copper plating are formed on the outermost surfaces of at least those portions of the strap rings 161, 162 which are connected to the vanes 102, and second layers 13 of silver plating are formed below the first layers 12 to perform brazing.