Manufacturing method of gas saving device

The invention provides a manufacturing method of a gas saving device. The purpose of the present invention is to reduce the size of a product and simplify the position adjustment of a fully closed stopper or the like. A method for manufacturing a throttle device, the throttle device comprising: a throttle body; a throttle valve; a throttle gear; a spring member; a fully-closed stopper mechanism including a body-side fully-closed contact surface on the throttle body side and a gear-side fully-closed contact surface on the throttle gear side; and an initial opening stopper mechanism including an abutting surface of an initial opening restricting portion provided integrally with the spring member, and an initial opening restricting stopper abutting surface on the throttle body side. At least one of a main body-side fully-closed contact surface, a gear-side fully-closed contact surface, a contact surface of an initial opening restriction section, an initial opening restriction stopper contact surface, a contact s