Dental problems among athletes have been cautioned due to negative impacts not only on their oral health but also on athletic performance. Acquirement of appropriate oral health behavior mainly composed of toothbrushing in childhood can be one of the most important strategies for advancing children’s athletic possibilities. Although habits of screen viewing, including game playing, and TV viewing have direct impacts on children’s health and behavioral development, little is known about the association between these habits and toothbrushing frequency. A cross-sectional survey examining sports activities was conducted using a self-report questionnaire among school-aged athletic children belonging to the Miyagi Amateur Sports Association (n = 6,658). All statistical analyses were performed with SPSS, and P-values less than 0.05 were considered statistically significant. The association between a lower brushing frequency (< 2 times a day) and screen-viewing behavior was examined using multivariate logistic models after adjusting for sex, age, body mass index (BMI), studying time, and sleep duration. After adjustment for all covariates, longer game playing (> 2 hrs a day), but not TV viewing, significantly correlated with lower brushing frequency (P for trend < 0.001). Importantly, longer game-playing behavior was also associated with unhealthy dental behavior defined as a lower brushing frequency regardless of the awareness of dental caries (P for trend < 0.001). In conclusion, this is the first study indicating a type-specific unfavorable impact of screen viewing on oral health behavior among athletic children. Excessive game playing may adversely affect oral health literacy more strongly than TV viewing.