Objectives: To investigate the current state of primary palliative care practice in Japanese critical care settings, identify care perceived as equivalent to primary palliative care, and explore the barriers. Methods: We employed a quantitative descriptive questionnaire survey with a nationwide cross-sectional design involving 740 critical care specialist nurses. Results: Questionnaires were received from 384 nurses, yielding a response rate of 51.9%. Nurses recognized typical palliative care provided to cancer patients, such as “relieving suffering at end-of-life” (95.3%), “pain management” (88.8%), and “caring for patients’ psychological suffering” (88.3%), as primary palliative care in the critical care setting. They also recognized “monitoring and management of delirium” (68.5%), “caring for patients’ social suffering” (63.5%), and “preventing post-intensive care syndromes” (61.7%) less frequently as aspects of primary palliative care in critical care settings. Additionally, the recognition was lower among emergency department nurses than intensive care unit nurses. The nurses recognized inadequate overall palliative care practices, especially regarding patients’ social (72.1%) and spiritual (76.8%) suffering. They recognized “insufficient knowledge and skills among critical care medical staff” (70.6%) and “unable to confirm the patients’ preferences to treatment goals” (54.4%) as barriers to providing primary palliative care. The barriers that nurses recognized less often were “uncertainty about palliative care in critical care settings” (6.8%) and “disagreements among nursing teams regarding providing palliative care” (8.3%). Conclusion: Specialist nurses understood palliative care but felt unprepared in primary palliative care due to limited knowledge. Improved education in primary palliative care and patient-family communication is needed in Japan’s critical care settings.