A spark plug having a center electrode, a ground electrode, and a noble metal tip that is joined to a part of the ground electrode near one end of the ground electrode via a fused portion. The fused portion extends outward beyond an outer shape of the noble metal tip so that a part of the fused portion is present at each of positions that are located inward from and separated from both side edges of the ground electrode in a width direction of the ground electrode. The fused portion includes a fused protrusion that is located near at least one of two side edges of the noble metal tip in the width direction of the ground electrode and that protrudes in a direction away from the one end of the ground electrode.