A 60-year-old man presented with a rare case of primary angiitis of the central nervous system mimicking a tumor-like lesion and manifesting as slight disorientation, left hemiparesis, and motor aphasia. Computed tomography showed multiple low density lesions in the left frontal lobe, brain stem, and right parietal lobe. Magnetic resonance images revealed a slightly enhanced mass lesion in the right parietal lobe with surrounding brain edema. Serum, cerebrospinal fluid, and other image examinations did not show any abnormal findings, so surgical removal of the right parietal mass was performed. Histological examination revealed that the mass consisted of hemorrhagic infarction without cellular atypia. Proliferations of endothelial cells in small and medium arteries, and infiltration of macrophages in the perivascular space were detected in the infarction tissues. The histological diagnosis was primary angiitis of the central nervous system.