A 57-year-old woman presented with a fever and left-sided hip and back pain. The hip pain was explained by L3 radiculopathy because the pain was distributed on the L3 dermatome accompanied by allodynia. On the other hand, the back pain was located on the left side 1 cm from the spinal process of the L3-4 vertebrae. Enhanced computed tomography of the abdomen revealed an abscess in the left paravertebral muscle, and pyomyositis was diagnosed. Following percutaneous drainage via ultrasound, both the hip and back pain immediately improved. Paraspinal pyomyositis as well as lesions inside the spinal canal should therefore be considered in the differential diagnosis of patients presenting with fever, back pain, and radiculopathy.