OBJECTIVES: This study aimed to clarify the relationship between oral function and life-space mobility or social networks in order to explore approaches that prevent a decline in oral function. MATERIALS AND METHODS: A total of 113 community-dwelling older people (mean age; 75.7 ± 7.3 years) who participated in preventive long-term care projects aimed at the maintenance or improvement of physical and mental functions were included in this study. The life-space assessment (LSA) was used to evaluate life-space mobility, while the Lubben Social Network Scale-6 (LSNS-6) was employed to assess social networks. Oral function was measured by maximum voluntary tongue pressure, oral diadochokinesis, the repetitive saliva swallowing test, and lip pressure. Indices of frailty were grip strength and the Kihon Checklist score. Multiple regression analysis was performed to clarify whether the LSA, LSNS-6, and frailty are associated with oral function. RESULTS: The results of the Kihon Checklist showed that 63 participants (56%) were subjectively and at least slightly aware of a decline in oral function. LSA (B = 0.222, p < .001) and grip strength (B = 0.266, p = .003) associated with maximum voluntary tongue pressure. The goodness of fit of the predictive model was an adjusted R2 value of .486. Other oral functions were not associated with any factors and the goodness of fit of the model was poor (Adjusted R2  < .1). LSNS-6 was not associated with any oral function. CONCLUSIONS: Life-space mobility and grip strength were independent factors associating maximum voluntary tongue pressure, while social networks did not directly association oral function. This study suggests the necessity of a program that approaches both oral and physical functions through guidance for securing a certain amount of daily activity for older people at risk of or exhibiting a decline in maximum voluntary tongue pressure.