according to an aspect of the present invention , there is provided an abnormality judgment device including : a change amount calculator configured to calculate a change amount between currently - obtained and previously - obtained steering angles ; a storage section configured to store a threshold value ; a reference setting section configured to set a reference steering angle ; an incrementing section configured to continue gradually incrementing the threshold value after the change amount exceeds the threshold value , for a judgment time ; a deviation comparator configured to compare an absolute deviation between the currently - obtained steering angle and the reference steering angle with the threshold value , and to count a counter when the absolute deviation exceeds the threshold value ; and a judgment section configured to judge that the steering angle sensor is abnormal when the counter reaches a predetermined value .