Social support could help immigrant Chinese women in Japan to improve health. However, these women suffer from numerous stresses associated with acculturation and child-rearing, which could impact the effect of social support on mental and physical health. This study aims to identify the relationships among social support, acculturative stress, parenting stress, mental health, and physical health to propose a structural path model of these relationships and to evaluate the mediating role of stress between social support and health. A questionnaire was used to collect data for the main variables and demographic factors. A total of 109 women participated (mean age 33.9 ± 5.6 years). The results show that immigrant Chinese women in Japan experienced a low level of mental health (44.7 ± 9.8). Additionally, social support directly influenced parenting stress (β = −0.21, p < 0.05), acculturative stress (β = −0.19, p < 0.05), and mental health (β = 0.31, p < 0.001) and indirectly influenced physical health (β = 0.09, p < 0.05). Parenting stress partially mediated the association between social support and mental health (β = 0.09, p < 0.05). To protect the effectiveness of social support on mental health, it is essential to reduce the parenting stress of immigrant Chinese women.