To inhibit vapor in a fuel flowing to a second fuel distribution path by shortening a fuel communicating pipe between first and second fuel distribution paths in respective sides of a throttle body, first and second throttle bodies (1, 3) are arranged in parallel, first and second throttle valves (8, 9) are attached to a single throttle valve shaft (5), a throttle drum (6) is attached to a left end (5c) of the throttle valve shaft (5), first and second fuel supply bodies (10, 11) including first and second fuel injection valves (J1, J2) are arranged respectively in one side (B) and the other side (A) of the throttle bodies, both the fuel supply bodies (10, 11) are connected by a fuel communicating path (16), and the fuel communicating path (16) is arranged inn a space among throttle valve shaft (5), upper ends (1x, 3x) of the throttle bodies, opposing side surfaces of both the throttle bodies (1, 3).