This study aimed to reveal the clinical features requiring sacroiliac joint (SIJ) arthrodesis, which was performed for patients who complain of severe SIJ pain.The differences in clinical features between a surgical treatment group (n=20) and a conservative treatment group (n=66) were investigated. All patients were definitively diagnosed with SIJ pain by the use of SIJ injections.Six significant features were identified in the surgical treatment group, namely, sitting tolerance (?6 months of continued substantial conservative treatment. J. Med. Invest. 70 : 123-128, February, 2023.