We present the case of a 74-year-old woman complaining of blurred vision in the left eye who was found to have a unilateral, continuous lesion of the optic nerve and nerve sheath accompanied by an intracranial mass next to the cavernous sinus and meninges. Surgical decompression of the left optic nerve in the optic canal and partial resection of the mass followed by prednisolone administration were successful. Immunohistochemical analysis disclosed abundant infiltration of IgG4-positive plasma cells at >10 cells/high power field. These findings indicated a new pattern of compressive optic neuropathy with confirmed IgG4 histopathological findings. Such an extensive lesion may produce visual disturbance.