To precisely complete the adjustment of two fuel adjusting means by one work in a carburetor for a spark ignition internal combustion engine to which a method for adjusting fuel of a low-speed system by two different fuel adjusting means in two different throttle valve openings to reduce the dispersion of a fuel flow rate in the vicinity of a throttle valve opening range is applicable.

In this carburetor, a structure in which the result of the fuel flow adjustment by one fuel adjusting means in at least one throttle valve opening has no influence on the fuel flow rate in the other throttle valve opening is adapted.