To provide a magnetron which can remove a failure of slipping-out of soldering between a strap ring and a vein taking into consideration of a parts dimension tolerance and a silver plating thickness and the like.

This magnetron is provided with an even number of veins 12 which are united to the inner circumference of a positive electrode cylinder 11 radially disposed to a negative electrode that is disposed at the center of the positive electrode cylinder 11. To every other veins 12 an inner strap ring 13 and an outer strap ring 14 are welded alternately. Each the vein 12 is provided with a welded surfaces 12a, 12a which are welded to inner circumferential surfaces 13a, 14a of corresponding strap rings 13, 14, and projecting parts 12b, 12b are formed at the welded surface 12a, 12a.