To establish possibility of adding a starter to a diaphragm type carburetor by making it possible to start a mowing machine, etc., in its rotating range in which blades refrain from rotation for the sake of safety, i.e., idle starting, and suppressing low the rise of the costs of carburetor.

A fuel passage 45 for starting leading to an intake passage 3 downstream of a throttle valve is connected in a position between a check valve 34 in a main fuel passage 6 and a throttle part 18 of a fuel nozzle 5 or a main jet 31 and is furnished with a start valve 46 so that it is opened and closed. When the engine is started by opening the start valve 46, the intake negative pressure downstream of the throttle valve 4 is fed to the fuel passage 45, and a fuel for starting is sucked out from the main fuel passage 6 to the intake passage 3 while the air measured by the throttle part 18 or main jet 31 flows in from the fuel nozzle 5 and is mixed with the fuel to be supplied to the engine, where a certain minor quantity of air is increased, and a mowing machine, etc., can be started at a revolving speed at which blades refrain from rotation.