Gas sensor

A gas sensor comprising:

• a sensor element extending in an axial-line direction, and having a detection portion on a front-end side and an electrode pad at an outer surface on a rear-end side;
• a metal terminal extending in the axial-line direction and electrically connected to the electrode pad;
• and
• a tubular separator having a passage hole extending along the axial-line direction, the separator storing the metal terminal inside the passage hole and surrounding the electrode pad of the sensor element, wherein
• the metal terminal has
• a plate-shaped body portion extending in the axial-line direction and supported inside the passage hole, the body portion having a main surface,
• a first engagement portion, which is a cut-and-raised cantilever tab formed from the main surface of the body portion, capable of protruding/sinking outward/inward from the main surface, and
• a second engagement portion located on the front-end side relative to the first engagement portion and connected to the body portion, the second engagement portion protruding in a main-surface direction of the body portion while being flush with the main surface,
• the separator further has a ledge portion having a first rearward-facing surface contiguously to the passage hole, and a first frontward-facing surface formed on the front-end side relative to the first rearward-facing surface contiguously to the passage hole,
• the first engagement portion is formed such that a rear-end side of the cut-and-raised cantilever tab is connected to the body portion, a front-end side of the cut-and-raised cantilever tab is an unconstrained tip that is free to protrude/sink outward/inward of the main surface, and the front end is opposed to the first rearward-facing surface, and
• in the main-surface direction, regarding the passage hole, a maximum opening width W2 of each retention hole retaining the metal terminal one by one satisfies a relationship of W2<W1 with respect to a maximum width W1 of the metal terminal at a part where the second engagement portion is located.