To provide a motor which achieves higher output by improving cooling efficiency in the motor with a simple structure.

Hole parts 17 are radially provided in an outer rotor holding part 8-a, and grooves 16 are provided at the shaft side of the outer rotor holding part. Air in the motor which flows near the grooves 16 is exhausted to a rotor outer peripheral part by a centrifugal force, and outside air flowing around the grooves 16 is guided from openings 6. The outside air is blown onto a coil part 4 located in the middle of the airflow path to effectively cool the coil part 4.