Objective Our previous study suggested that monitoring online board gamers may be an efficient approach to curb illegal gambling. We aimed to invent and validate a behavioral scale for assessing the risk of problematic web-based board gaming. Methods The sample included 300 Korean adults, representing a response rate of 3.1%. All participants were asked to complete a set of questionnaires, which included questions on demographic variables, patterns of online board gaming, and the web-based board game scale score. Exploratory factor analysis was performed to determine whether the items on the new behavioral scale would indicate a risk of pathologic web-based board gaming behavior. Results The internal consistency of the 17-item scale was high (Cronbach’s α=0.89). The test-retest reliability of the 17-item scale in a randomly selected sample of 100 participants in 2 weeks was r=0.77 (p<0.001). The criterion-related validity based on a comparison of the total behavioral scale scores between the high-risk group and low-risk group was relatively high. The data obtained from the 300 participants were acceptable for a factor analysis. After removing 7 items from the 17-item scale, internal consistency (Cronbach’s α) of the 10-item scale increased to 0.936. Conclusion These results showed that the 10-item version of the scale appeared to be more valid than the 17-item version. We suggest that the 10-item web-based board game behavioral scale is a useful tool for assessing the risk of pathologic web-based board gaming.