Abstract: A ventilating device in a power driven tool has a fan driven by a motor for cooling the motor and has an air flow channel for the air to flow to the outside after passing around the motor. The ventilating device includes an air passage member disposed in the air flow channel on the downstream side of the fan to form a part of the air flow channel. The air passage member includes a plurality of blow windows and a plurality of partition walls for separating the blow windows from each other. The blow windows are positioned in series in the rotational direction of the fan. The partition walls have different heights relative to and in the direction toward the fan such that the heights increase in the rotational direction of the fan.