A portable rotary saw includes a cooling fan fastened to the output shaft of a motor and a plurality of ports provided downstream of the fan in a blade case defining a blade chamber. The ports allow the cooling air delivered by the fan to blow further downstream in the housing of the portable rotary saw. The portable rotary saw further includes a cover plate provided in front of the ports for separating a pathway of a wind caused by a rotating saw blade and for directing the cooling air out of the blade chamber without disturbing the wind caused by the rotating saw blade.