PURPOSE: To absorb strain due to a difference in thermal expansion between metallic parts, etc., by fine particles by connecting a metallic flanged pipe to the inside electrode of a solid-state electrolyte pipe electrically, and pressing its flange part fixedly by an insulator and the fine particles.

CONSTITUTION: The outside electrode 7 of the solid-state electrolyte pipe 1 is fitted to a metallic socket 2, and the inside electrode 8 is connected electrically to the metallic flanged pipe 15 having the flange part in the middle. The flange part is pressed by the insulator 16 toward the solid-state electrolyte pipe 1 and this insulator 16 is fixed by the heat-resisting fine particles 17, a metallic casing 5, and a spacer 18. Consequently, even when there is a difference in coefficient of thermal expansion among the solid-state electrolyte pipe 1, insulator 16, and other metallic parts, etc., the strain due to the difference is absorbed by the fine particles 17, so stable performance is held for a long period.