A method for manufacturing a gas sensor, said method including a step of obtaining an assembled body constituting said gas sensor by performing a predetermined processing on a semi-assembled body (40α) which is manufactured in advance, and said semi-assembled body (40α) comprising: an annular-mounted assembly in which a plurality of annularly-mounted members (7, 8, 9), at least one of which is a ceramic powder compact, each having a disc shape or cylindrical shape are annularly mounted to a sensor element with an elongated plate shape which is made of a ceramic; and a tubular body which is annularly mounted to an outer periphery of said annularly-mounted members (7, 8, 9) and capable of engaging one end side of said annularly-mounted members therein, and said step of obtaining said assembled body comprising steps of: a) causing one end of said sensor element constituting said manufactured semi-assembled body (40α) to abut to a positioning member for positioning said sensor element; b) applying a first force to said annularly-mounted members (7, 8, 9) from other end side of said sensor element having been positioned through said step a) and thereby compressing said powder compact so as to fix said sensor element inside of said tubular body; and c) after said step b), applying a second force which is larger than said first force to said annularly-mounted members (7, 8, 9) from said other end side of said sensor element with said one end of said sensor element not abutting to said positioning member and thereby further compressing said powder compact so as to hermetically seal between spaces located on one end side and said other end side of said sensor element inside of said tubular body. an annular-mounted assembly in which a plurality of annularly-mounted members (7, 8, 9), at least one of which is a ceramic powder compact, each having a disc shape or cylindrical shape are annularly mounted to a sensor element with an elongated plate shape which is made of a ceramic; and a tubular body which is annularly mounted to an outer periphery of said annularly-mounted members (7, 8, 9) and capable of engaging one end side of said annularly-mounted members therein, and said step of obtaining said assembled body comprising steps of: a) causing one end of said sensor element constituting said manufactured semi-assembled body (40α) to abut to a positioning member for positioning said sensor element; b) applying a first force to said annularly-mounted members (7, 8, 9) from other end side of said sensor element having been positioned through said step a) and thereby compressing said powder compact so as to fix said sensor element inside of said tubular body; and c) after said step b), applying a second force which is larger than said first force to said annularly-mounted members (7, 8, 9) from said other end side of said sensor element with said one end of said sensor element not abutting to said positioning member and thereby further compressing said powder compact so as to hermetically seal between spaces located on one end side and said other end side of said sensor element inside of said tubular body. a) causing one end of said sensor element constituting said manufactured semi-assembled body (40α) to abut to a positioning member for positioning said sensor element; b) applying a first force to said annularly-mounted members (7, 8, 9) from other end side of said sensor element having been positioned through said step a) and thereby compressing said powder compact so as to fix said sensor element inside of said tubular body; and c) after said step b), applying a second force which is larger than said first force to said annularly-mounted members (7, 8, 9) from said other end side of said sensor element with said one end of said sensor element not abutting to said positioning member and thereby further compressing said powder compact so as to hermetically seal between spaces located on one end side and said other end side of said sensor element inside of said tubular body.