The pre-tilt direction of a liquid crystal (LC) on a polyimide (PI) surfaces obtained by using a contact angle method is systematically examined. We found from scanning probe microscopy (damping force microscopy and friction force microscopy) data that ion-beam-treated PI surfaces have an asymmetrical morphology which determines the preferred direction of the LC. Azimuthally various contact angles on an ion-beam-treated PI surface are connected deeply with modified surface morphologies. As a result, the effect of LC pre-tilt direction on ion-beam-treated PI is to lower the contact angle direction.