The aim of the present study was to compare risk factors for problematic Internet use (PIU) among Japanese and Chinese university students. A sample of 267 Japanese and 236 Chinese first year university students responded to questionnaires on the severity of PIU, depression, self-image/image of others, and perceived parental child-rearing styles. The results indicated that Japanese participants were more likely to demonstrate PIU than their Chinese counterparts. Compared to Chinese students, Japanese students reported more negative self-image, lower parental care, greater overcontrol, and higher depression scores. The PIU group had a higher depression score compared to the normal Internet use group. Compared with the non-PIU group, the PIU group consisted of more male and Japanese participants. Further, they tended to have more negative self-images, saw their mothers to be less caring, and perceived their mothers and fathers as more overcontrolling. PIU is strongly associated with depression, negative self-image, and parental relations. Finally, mediation analysis revealed that such national differences in PIU between Japanese and Chinese were clarified in depression and perceived mother's care. This cross-national study indicated that depression and perceived mother's care were both significant risk factors that were associated with the national difference in PIU between Japanese and Chinese participants.