A gas sensor 1 includes a sensor element 2, a housing 13 and an element cover 3. The sensor element 2 is provided with a gas introduction part 271 for introducing a measurement gas thereinto at a distal end portion 201 thereof. The element cover 3 includes an inner cover 4 disposed so as to cover the distal end portion 201 of the sensor element 2 and an outer cover disposed outside the inner cover 4. The outer cover 5 is provided with outer inlet openings 52 for introducing the measurement gas into the outer cover 5. The inner cover 4 is provided with inner inlet openings 42 for introducing the measurement gas into the inner cover 4. The axial intermediate position C1 of the gas introduction part 271 of the sensor element 2 is more to the axial proximal end side X2 than the axial proximal end position D1 of the inner inlet opening 42 of the inner cover 4.