an electric power tool includes a tool body having a rotor , an inner cylindrical body and outer cylindrical body . the rotor is provided with a ventilation space therearound , a body part and a brush contact part , and housed in the inner cylindrical body . the inner cylindrical body is inserted in the outer cylindrical body which has a plurality of groove - like ventilation spaces on its inner face . the rotation of a fan fitted on the rotor circulates air within the tool body through the ventilation spaces so as to cool down the body part and the brush contact part of the rotor . the electric power tool has the rotor with which not only the body part but also other heated parts are fully cooled down . the electric power tool enhances heat dissipation efficiency from a motor case , enables efficient cooling of heated parts and has a long durability .