PURPOSE: To realize first idling action automatically according to the temperature by using the captioned device for a carburetor of an engine and the like.

CONSTITUTION: A choke arm 6 is fixed to a choke valve shaft 5, and a choke lever 7 is rotatably supported, while one end part 8a of a coil-shaped spring 8 arranged round the choke valve shaft 5 is engaged with the choke arm 6 and the other end part 8b is engaged with the choke lever 7. The spring 8 is adjusted so that its load working on a choke valve 2 due to its own torsion is almost zero where the temperature is 20°C and said valve 2 is fully closed. A choke valve adjustment system 4 has a substence 12 and works on the choke lever 7. At the time of low temperature, the substance 12 contracts and rotates the choke lever 7 counterclockwise, subsequently a twist is given to the spring 8, then resistance is given to opening of the choke valve 2, and said valve is closed. A throttle valve 3 is moved in linkage with the lever 7 through a link 11 and opened widely.