Abstract: Objective To investigate the relationship between internet addiction and the sense of responsibility in middle school students.Methods Using the adolescent pathological internet use scale(APIUS) and the sense of responsibility questionnaire for middle school students,a sample of 654 middle school students in Huzhou city of Zhejiang province were tested.Results The proportion of internet addiction disorder in the middle school students was 6.7%,and that of marginal internet addiction was 3.7%.The rate of internet addiction in high-school students(9.4%) was significantly higher than that in junior middle school students(3.8%).The rate of internet addiction in male students(6.9%) was significantly higher than that in females(1.2%) in junior middle schools,and the rate of internet addiction in male students(13.6%) was higher than that in the females(6.2%) in high-schools,with significant differences.The sense of responsibility of normal middle school students was higher than that of the students with internet addiction disorder or marginal internet addiction.The score of global responsibility,general task responsibility,general negligence responsibility,and the scores of factors of task responsibility and negligence responsibility were all significantly related inversely with the total average score of internet addiction(r=-0.140- -0.463).The scores of global responsibility,general task responsibility,general negligence responsibility,and the scores of task academic responsibility,task family responsibility,negligence academic responsibility,and negligence family responsibility could inversely predict the total average score of internet addiction(β'=-0.101- -0.299).Conclusion The internet addiction disorder of middle school students was related with their sense of responsibility.