High-voltage capacitor and magnetron

An earthing device (1) has two rise parts (101, 102) and through-type capacitors (2, 3) fastened to the tops of the parts (101, 102). In an insulation case (6), two tubes (61, 62) are provided in parallel with each other at a space (D). The upper parts of the tubes (61, 62) have openings forming a recess (63) in the top of the case (6); the lower parts of the tubes (61, 62) forming a recess in the bottom of the case (6) are secured to the outer peripheries of the rise parts (101, 102). The spaces around the through-type capacitors (2, 3) are filled with insulating resins (71, 72). Thereby, a small cheap high-voltage capacitor which has a large mechanical strength and good withstand voltage characteristics including a good wet withstand voltage characteristic can be manufactured.