In this paper, the cooling airflow in a unidirectional ventilated open-type motor for electric vehicles (EV) was studied. Numerical fluid analysis was performed on the airflow in the motor through a ventilation path outside the stator iron core inside the frame. It is confirmed that there was a flow separation where air did not flow along the path surfaces. This was observed in a flow visualization experiment using water instead of air.,We propose a new structure to prevent air separation and confirm its effectiveness by a visualization experiment. It is also shown that another structure with paths both inside and outside the stator iron core in the frame improves the motor's cooling performance. These structures are effective for EV motor downsizing.