A brushless motor includes a motor holder and a case connected thereto. A ventilation chamber is defined between the motor holder and the case. The ventilation chamber includes an air inlet portion, an air outlet portion and water draining portions. The air inlet portion is in communication with the atmosphere. The air outlet portion is in communication with a stator. The water draining portions drain water introduced into the ventilation chamber out of the motor. The motor provides a flow of cooling air passing through the ventilation chamber toward the stator for cooling heat generated during rotation of a rotor. The motor holder and the case have guide ribs arranged in the ventilation chamber to define an air passage for guiding the cooling air from the air inlet portion to the air outlet portion. The water draining portions are located outside of the air passage.