An apparatus and a method for diagnosing optic neuropathic diseases including glaucoma, are provided. The apparatus for diagnosing optical neuropathic diseases measures a thickness of a retinal nerve fiber layer (RNFL) using methods such as optical coherence tomography (OCT) and scanning laser polarimetry, and includes a scanning unit which scans along an optic nerve margin in the proximity of an optic nerve head, a pattern analyzing unit which analyzes a pattern of the RNFL scanned by the scanning unit, and a disease determining unit which determines a presence of the disease based on the pattern of the RNFL analyzed by the pattern analyzing unit.