Abstract: To prevent back bleed in a carburetor including a slow fuel passage branched from a main fuel passage, in a carburetor for an engine in which a slow air intake port to introduce air into a slow air bleed passage opens on the side of a suction passage; a slow fuel passage is connected in the middle of a main fuel passage on the upstream side, joins the slow air bleed passage on the downstream side, and has an open end on the side of the suction passage; and the main fuel passage opens in a state where a main nozzle projects in a venturi part of the suction passage, wherein the slow air intake port is opened at a predetermined position of the venturi part having an inner diameter equal to or less than that of the suction passage at a position where the main fuel passage opens.