To prevent an air tool from emitting noises when a high pressure air is supplied to the air tool for its actuation and the air after the work is to be exhausted via an exhaust passage positioned inside the tool body by decreasing the exhaust sound during the air flowing through the exhaust passage.

An exhaust passage provided inside the tool body is partitioned by a bulkhead having a narrow passage in the form of slit, etc., into at least two chambers, a first and a second expansion chamber, and the air discharged into the first chamber is dispersed and decelerated for reduction of the sound, and further is passed through the narrow passage in the bulkhead and dispersed and decelerated for further reduction of the sound, and then is allowed to flow out from the discharge port having a smaller section area than the expansion chamber. Thus an enhanced silencing effect is established.