Patent ID: 8393196

Claim:
A gas sensor comprising: a gas sensing layer which is formed on a base member and which includes, as a main component, a metal oxide semiconductor having an electric characteristic varied in accordance with variation of a concentration of a specific gas in a measurement gas; characterized in that the gas sensor further comprises: a pair of sensing electrodes formed on the base member and arranged to sense variation of the electric characteristic of the gas sensing layer; and an adhesion layer contacting with the gas sensing layer; the sensing electrodes being in contact with the gas sensing layer, but not in contact with the adhesion layer; and that the base member includes: a semiconductor substrate formed with an opening portion extending in a thickness direction, an insulating layer which is formed on the semiconductor substrate and which includes a separating wall portion formed at a position confronting the opening portion, a heat generating resistor formed on the separating wall portion, and a protection layer formed on the insulating layer to cover the heat generating resistor; and the sensing electrodes, the adhesion layer, and the gas sensing layer being formed on the protection layer of the base member.