The Internet is one of the most widely accessible media in the world. Adolescents are required to learn about it for academic and recreational reasons, however, addiction to the Internet has resulted in negative impact on academic performance, family relationships, and emotions for adolescents [1] and [2]. This phenomenon has been defined as Internet addiction [3] and reported to be associated with depression and attention deficit hyperactivity disorder (ADHD) [4]. However, Shaffer et al have countered that there is not yet sufficient construct validity to establish it as a primary disorder and it is better explained by other primary disorders [5]. Because comorbidity of two disorders may indicate the causal relationship or common etiology shared by them [6], the evaluation for comorbid psychiatric symptoms of Internet addiction could reveal which psychiatric symptoms are associated with the development or maintenance of the Internet addiction, and shed light on the mechanism of Internet addiction.