Abstract: In order to find out the relationship between smart phone addiction and the five big personalities, the Smart
Mobile Phone Addiction Scale and the Big Five Personalities Scale were adopted to test203 junior middle school students, trying to find out about the relationship between the various variables by means of the independent samplet-test, F-test and the stepwise regressive analysis. It is found that the smart phone addiction among junior students is rather high and no significant difference is found between genders. In terms of the scores, the left-behind students score significantly higher than those not-left-behind students; students with a smart phone score significantly higher than those who have none. Among the junior students, the human friendliness and sense of respongsibility have a significanly positive predictive power for smart phone addiction formation. And the cultivation and forming of an excellent personality will be crucial in the prevention of smart phone addiction.