As the method to analyze the operating motion of the small fishing boat, the kinematic GPS is used. However, this method is hard for the small fishing boat to set up the measurement equipments. As for the reasons, there is almost no setting space for the equipment and supply of the power source. Therefore, the authors examined the portable GPS logger as an alternative way. As a result, by setting up the portable GPS in longitudinal direction of the fishing boat (the small boat) in pairs, the heading angle of the operating fishing boat could be acquired in a certain accuracy.