A pneumatic tool contains: a body, a drive unit, a piston element, at least one buffer, and a movable air tube. The body includes an intake head, a limiting sleeve, a switch, an air conduit, and a connection portion. The connection portion has a first guide element, a first guiding orifice, and the limiting sleeve has a shoulder. The drive unit includes a moving tube, a first segment, and a second segment. The moving tube has a protrusion, the second segment has a second guide element and a second guiding orifice. The moving tube has a coupling orifice and a cavity, and an air valve is defined between the cavity and the second guide element. One buffer is defined between the first guide element and the second guide element and includes a first through hole. The movable air tube includes an air inlet segment and an air outlet segment.