Patients in the ICU are often treated under extreme conditions, with the patient often fearful of losing his life or experiencing severe pain. As a result, high-quality pain management is required. However, response to pain is often inadequate due to continuous administration of sedatives, difficulties in communicating with intubated patients, and/or poor awareness of pain in patients not receiving surgery. Reports on difficulties in pain management in the ICU are many, but few consider the correlation between pain management and patient prognosis. Consequently, consideration on how to implement pain control activities in the ICU to improve patient prognosis is needed.