PURPOSE: To improve discharge voltage characteristics as well as to exhibit spark plug characteristics required by the increasing high performance of an internal combustion engine while spark consumption performance is positively being secured by forming an ignition electrode out of a clad structure consisting of an improved spark resisting material and a reduced discharge voltage material.

CONSTITUTION: In a spark plug 1 for an internal combustion engine, a spark electrode 3 with a clad structure wherein alloys of more than two kinds are clad in the radial direction, is joined to the tip end of a control electrode 4. The plug is formed out of the control electrode 4, an insulating material 2 which encloses a terminal electrode 11 while a resistor 13 is being held by a conductive glass seal member 10 so as to be secured within an axial hole 12 wherein an outside electrode 7 which is faced with the spark plug electrode 3, is arranged, and out of a main body fitting 5 with a screw section 6 required to be fitted onto the internal combustion engine. An improved spark resisting material to be used at the center section shall be a Pt-10 to 30% Ir alloy, and a reduced discharge voltage material to be used for the outer circumferential section covering the center section shall be a Pt-20 to 60% Ni alloy or a heat resistant Ni alloy.