Provided is a method for manufacturing a gas sensor which suppresses a defective product caused by a defective posture of a sensor element therein. The method includes a step of obtaining an assembled body constituting the gas sensor, including steps of: causing one end of the sensor element to come to abut to a positioning member for positioning the sensor element; and applying a first force to the annularly-mounted members including a powder compact annularly mounted to the sensor element under a state that the sensor element is positioned and thereby compressing the powder compact so as to fix the sensor element inside of the tubular body, and the compression is performed while constraining the sensor element in a predetermined constraining region in the other end side of the sensor element.