Spark plug and method for manufacturing spark plug

Abstract

This invention has an object to provide a spark plug exhibiting high withstand voltage characteristics and high strength at high temperature, formed by an alumina-based sintered body prepared with excellent processability and high productivity, and a method for manufacturing the spark plug. This invention relates to a spark plugincluding an insulator, wherein the insulatorincludes a dense alumina-based sintered body having an average crystal particle diameter of 1.50 μm or more, and the alumina-based sintered body contains Si, a Group 2 element component containing Ba and a Group 2 element other than those, and a rare earth element component, such that a ratio of a content S of the Si component to a total content of the content S and a content A of the Group 2 element component is 0.60 or more, and a method for manufacturing the spark plugprepared through a grinding-shaping process in which the insulatoris ground before burning to shape the same.