Spark plug and producing method thereof

摘要

In a spark plug in which a space between a center electrode at the top end side and a terminal electrode at a rear end side which are arranged to be opposite to each other in an axial hole of an insulator, the glass seal is effected at a temperature within the range of 500 to 1000 DEG C. and under a condition where the concentration of oxygen is 12 vol % or less.