A high-voltage feed-through capacitor includes: a capacitor element; a grounding metal fitting; an insulating resin; two through conductors; an insulating cover; and an insulating tube. The capacitor element has two separate electrodes on one side and one common electrode on the other side and is mounted on one side of the grounding metal fitting with the common electrode being connected to the same side of the grounding metal fitting. The insulating resin fills a space inside the capacitor element. Each through conductor has a rod-like conductor portion passing through the grounding metal fitting and the capacitor element and connected to the separate electrode. At least a portion of the insulating tube is attached to the rod-like conductor portion within the capacitor element. The insulating cover is attached to the rod-like conductor portion to have one end thereof in contact with one end of the insulating tube.