To establish work environments that prevent Japanese nursing assistants from leaving their jobs, we investigated the associations between their job satisfaction levels and intentions to remain on their jobs. We distributed anonymous self-administered questionnaires to Japanese female nursing assistants in 30 different hospitals. Regarding job satisfaction, we investigated various items relevant to both intrinsic facets (e.g., gaining various experiences) and extrinsic facets (e.g., salary), and conducted factor analyses of those items. Standardized partial regression coefficients were then calculated using multiple regression analyses. Intention to remain on the job was the dependent variable for this study. The factor scores calculated by the factor analyses of job satisfaction and respondents' characteristics were the independent variables. Since multicollinearity occurred, we utilized two types of statistical models. After questionnaires with one or more missing values were excluded, 618 questionnaires were analyzed. Using factor analyses, we discovered six factors related to job satisfaction among nursing assistants: "Intrinsic motivation", "Salary", "Relationships among nursing assistants", "Registered nurses' attitudes", "Fatigue reduction", and "Opportunities for vocational skills". In statistical model 1, "Intrinsic motivation", "Salary", "Fatigue reduction", "Age", "Employment status", and "Certified care worker status" were significantly associated with "Intention to remain on the job". In statistical model 2, "Salary", "Registered nurses' attitudes", "Fatigue reduction", "Opportunities for vocational skills", "Age", and "Employment status" were significantly associated with "Intention to remain on the job". "Intrinsic motivation" and "Opportunities for vocational skills" are included in intrinsic facets. To prevent nursing assistants from leaving their jobs, raising only their extrinsic job satisfaction levels is insufficient. Because nursing assistants have not received formal nursing education, they cannot take pride in having the same skills and expertise as registered nurses. However, hospital managers must respect their feelings and establish an appropriate working environment.