An ignition plug includes an insulator that includes a through hole; a center electrode; a metal shell that holds the insulator; a bar-shaped ground electrode body; an electrode tip that is disposed along a side surface of the ground electrode body opposing a discharge surface of the center electrode; and a welding portion that is disposed between the ground electrode tip and the ground electrode body. Over ¼ of a range from a first end to a second end of the ground electrode tip, a length L1 of the ground electrode tip and a length L2 of the welding portion in the direction satisfy (L2/L1)≧0.25.