To simply carry out a complete correction of air/fuel ratio against an outstanding variation of an engine performance even in a small sized carburetor for a general purpose engine.

A constant bleed air passage 22 having a fixed jet 23 and a variable bleed air passage 24 having a closing valve 25 comprising a manual needle valve with screw and a fixed jet 26 are connected to a fuel route 15 for feeding a fuel in a constant fuel chamber 14 to an intake passage 2. An air-fuel mixture can be adjusted to the mixture of a predetermined air/fuel ratio over a wide correction width by restricting a high concentration side/a diluted side of the air/fuel ratio of the mixture by two fixed jets 23, 26 and adjusting a flow rate of the bleed air to a non-stage by the closing valve 25.