Japan, a super-aging society, faces a native care worker shortage and increased demand for foreign-born care workers (FBCWs) in geriatric care facilities. We investigated factors influencing native care workers’ concerns and reluctance toward accepting FBCWs in Japan from four areas. Native care workers (N = 1060) in 10 geriatric care facilities (response rate = 71%), recruited using convenience sampling considering the regional job vacancies, responded to a self-report questionnaire survey. After excluding ineligible data (e.g., for day-care facilities) or missing data, the analysis included 589 participants (67.2% women, Mage = 42.63 ± 12.16 years). Results indicated that facilities not accepting FBCWs had significant concerns about managerial positions and job stress. Native care workers with concerns about accepting FBCWs and those working 50+ hours per week were three times more reluctant to accept FBCWs. However, ethical leadership reduced this reluctance. Therefore, facility employers in aging countries must address native care workers’ concerns and ensure workplace improvement before hiring FBCWs.