This study investigated the relationships between psycho-social characteristics and playing the internet game time a day and internet game addiction of elementary school children. 170(boy 85, girl 85) sixth graders from the public elementary schools in Ulsan participated in the study. The results from the study were as follow: First, male children's scores on the internet game addiction and the playing game time were higher than those of female children. There was a significant difference in gender, academic engagement, sympathetic-receptive, social-friendly, competitive-aggressive, defiant-distrustful tendency, and a sense of inferiority respectively between the high score children and the low score children on the playing internet game time a day. Also, there was a significant difference on gender, academic engagement, and a sense of inferiority between the groups on the internet game addiction score, respectively. Second, sympathetic-receptive tendency and independent-responsible tendency were identified as significant predictors of playing internet game time a day respectively between the boys and girls. And sense of inferiority and independent-responsible tendency were identified as significant predictors of internet game addiction of boys. Sense of inferiority is the only powerful predictor of internet game addiction of girls. In sum, this study suggested that a prevention program for children's internet game addiction should focus on improvement of social and interpersonal relationship.