A spark plug is provided with a center electrode and a ground electrode. The ground electrode includes an electrode tip, an electrode base material, an intermediate member and a first melt portion. The intermediate member is disposed between the electrode tip and the electrode base material. The first melt portion contains components of the electrode base material and the intermediate member, and is disposed at least at a part of the boundary between the electrode base material and the intermediate member. In a cross section including the axis of the ground electrode, the boundary line between the intermediate member and the first melt portion has at least two first projection portions projecting toward the electrode tip side, and the boundary line between the electrode base material and the first melt portion has at least two second projection portions projecting toward the opposite side of the first projection portions.