To provide a secondary air supply device of a simple structure provided with an intake air control function more effectively preventing after burn in an exhaust pipe at a time of sudden deceleration of an engine.

A control valve controlling supply of secondary air to an exhaust port is connected to a diaphragm 12 operating with interlocking with vacuum in an intake pipe via a shaft 11. The shaft 11 is air-tightly inserted in a shaft bearing 18. A groove 11A is provided on the shaft arranged in the shaft bearing 18. Plot air passages 24, 25 supplying air to a pilot air jet of a carburetor are connected to the shaft bearing 18. The groove 11A communicates to the pilot air passages 24, 25 at a time of control valve open and the shaft 11 shuts off the pilot air passages 24, 25 in the shaft bearing 18.