PURPOSE: To perform spray of desired fuel by means of a certain amount of air, to stabilize the spray state through the reduction of the grain size of sprayed fuel, and to diffuse the sprayed fuel in the vicinity of an ignition part through the increase of a spray angle.

CONSTITUTION: A spray nozzle is so formed that an air nozzle 2 through which air for spray is blown and a liquid nozzle through which fuel is fed are coaxially arranged and fuel through the liquid nozzle 3 is sprayed by means of air blown through the air nozzle 2. A spray nozzle 1 is provided at the blow- off part of the air nozzle 2 with a collar 4 for revolutions having a plurality of notches having a given angle with the coaxial axis M of the air nozzle 2 and the liquid nozzle 3.