The prevalence of sacroiliac joint (SIJ) pain would appear to be about 10% of low back pain and the pain may develop in men and women of all ages. SIJ pain has not specific findings on CT and MR imaging. Pain area peculiar to SIJ pain is located laterally over the SIJ line, groin area (some cases). Most cases have numbness, pain not to correspond to sensory dermatome in leg, and tenderness on posterior superior iliac spine (PSIS) and around it, sacrotuberal ligament, iliac muscle. By one finger test, patients with SIJ pain may especially indicate PSIS and around it on iliac side. Diagnosis of SIJ pain is determined by diagnostic block. Most patients are adequately responsive to conservative treatments including SIJ block and stabilization by pelvic belts. SIJ arthrodesis is effective for patients with severe SIJ pain being markedly restricted their activities of daily living and working.