Spark plug with a corrosion impeding layer

A spark plug comprising:

• a center electrode;
• an insulating member disposed around said center electrode in a state that a top end of said center electrode is exposed at a top end of said insulating member;
• a main metallic shell provided covering at least a portion of said insulating member;
• a ground electrode forming a spark discharge gap between the top end of said center electrode and a top end of said ground electrode, and being positioned relative to the top end of said insulating member and the top end of said center electrode so as to allow creeping discharge to be performed along the surface of the top end of said insulating member;
• and
• a corrosion impeding layer formed on at least a portion of the surface of the top end of said insulating member,
• wherein at least one of said center electrode and said ground electrode contains at least one corrosion impeding component of a type contained in said corrosion impeding layer.