A throttle body (1) includes a throttle casing (2) and a motor casing (8). The throttle casing has a first main body (3) and a throttle valve (4) disposed within the first main body. The first main body is made of resin. The motor casing (8) has a second main body (9) and a motor (11) disposed within the second main body. The first main body and the second main body are formed separately from each other and are connected to each other via a joint device (27).