An ignition plug that promotes expansion of flame and enhances spark corrosion resistance, said plug includes a center electrode; a tubular insulator holding the center electrode; a tubular metallic shell holding the insulator; and a ground electrode having a bent portion and a facing end surface. A plurality of peak voltages can be applied to the center electrode after application of a voltage for trigger discharge thereto. When a forward end surface of the center electrode and the facing end surface are projected onto a plane orthogonal to axial direction of the center electrode, the projection of the center of the forward end surface and the projection of the facing end surface overlap with each other, and the projection of a remote-side edge portion of the facing end surface which is located on the side remote from the bent portion is located within the projection of the forward end surface.