Patent ID: 7154213

Claim:
A spark plug for a gas engine comprising a ground electrode body and a center electrode body, wherein a ground electrode of said ground electrode body is welded on a surface of a ground electrode base material opposing to said center electrode body; said ground electrode of said ground electrode body protrudes toward said center electrode body; said ground electrode is made of a material containing iridium or platinum as a main component; said ground electrode base material is made of a heat-resistant nickel alloy; said ground electrode is impacted in a recess of said ground electrode base material; and said spark plug satisfies the condition 0.3≦h/H≦0.5 when H represents a thickness of said ground electrode base material in an intrusion direction of said ground electrode, and h represents an intrusion length of said ground electrode that defines a length of said ground electrode impacted in said ground electrode base material in said intrusion direction.