Patent ID: 8721849

Claim:
An electrode holder, comprising: an electrode shaft having a first end as a terminal portion and a second end as a detection electrode portion; a container mounting portion formed of metal provided with a hexagonal head portion formed on an upper portion of the container mounting portion and a male thread portion formed on an outer periphery of a lower portion thereof, wherein a through-hole is formed along an axis of the hexagonal head portion and the male thread portion, and the electrode shaft is held coaxially in an interior portion of the through-hole; and an insulator formed of a synthetic resin configured to integrate the electrode shaft with the container mounting portion by mediating between an outer periphery of the electrode shaft and an inner periphery of the through-hole formed along an axis of the hexagonal head portion and the male thread portion, the electrode shaft passing through a hole portion of a metal container and being mounted to the metal container by the container mounting portion in a state where the electrode shaft is electrically insulated from the metal container by the insulator, characterized in that: the container mounting portion is provided with, in the through-hole formed along an axis of the hexagonal head portion and the male thread portion, a seat portion having a substantially ring shape and protruding in an orthogonal direction of the electrode shaft from the inner peripheral wall of the through-hole; the electrode shaft is provided with, on a surface thereof, an engagement protruding portion being spaced apart from the seat portion to the detection electrode portion side and having a larger diameter than a hole diameter of the seat portion, wherein the engagement protruding portion engages with the seat portion when the electrode shaft tries to burst out of the metal container from the container mounting portion; and the engagement protruding portion provided on the electrode shaft surface is positioned to be spaced apart from the seat portion by the insulator.