Arachnoid web is a very rare disease that occurs when the normal flow of cerebrospinal fluid is disturbed due to abnormal formation of the arachnoid membrane in the arachnoid space. Consequently, symptoms appear in the form of various myelopathies, such as loss of strength and sensation in the upper and lower extremities, or bladder control disorders. In general, surgical treatment can be considered if symptoms are exhibited. Arachnoid web requires a high consideration of appropriate diagnosis and treatment methods. However, due to its extremely rare occurrence in actual clinical practice, it is difficult to differentiate from other diseases such as herniated intervertebral disc or subdural tumor causing spinal myelopathy. This would effectively lead to a completely different direction of treatment. To date, there have been no case reports of Arachnoid web in Korea, except for collecting and reporting the focal anterior displacement of the thoracic spine, which is a similar lesion in the spinal cord. This article therefore provides information through case reports and literature review.