GAS SENSOR

Provided is a gas sensor capable of obtaining a stable sensor output quickly upon energization of a heater while reducing the amount of noble metal used on an inner surface of a base body. A gas sensor 30 includes an inner electrode 21 having an inner sensing portion 21g formed in a gas contact inner region 1kg such that the inner sensing portion 21g is located on the whole of a heat-facing area 1kt of the gas contact inner region 1kg facing a heating resistor pattern of a heating portion 33c in a radial direction of a base body 1, a terminal contact portion 21t formed in a rear end region 1kc such that the terminal contact portion 21t is located in at least a part of the rear end region 1kc in a circumferential direction of the base body 1 and a lead portion 21s formed only on a part of an inner surface 1k of the base body 1 in the circumferential direction of the base body 1 so as to connect the inner sensing portion 21g and the terminal contact portion 21t to each other.