1. A vehicle obstacle detecting device adapted to be mounted on a vehicle to detect an obstacle, comprising: a plurality of sensors including at least a first sensor having a sensing scope that does not substantially overlap a sensing scope of the second sensor thereby defining a blind spot between the sensing scopes of the first and second sensors; an obstacle behavior observing section configured to observe a behavior of an obstacle within at least the sensing scope of the first sensor; and a blind spot behavior predicting section configured to predict a blind spot behavior of the obstacle in the blind spot between the sensing scopes of the first and second sensors based on the behavior of the obstacle in the sensing scope of the first sensor observed by the obstacle behavior observing section.