A 59-year-old male developed peripheral oculomotor nerve paresis due to compression by the left posterior cerebral artery (PCA), which was successfully treated by microvascular decompression. Two months later, a similar oculomotor nerve paralysis due to the same mechanism occurred contralaterally and was also treated by microvascular decompression. The previous condition was probably caused by arteriosclerotic changes in the PCA, and the following condition by postsurgical adhesion of the arachnoid membrane. The possibility of vascular compression should be considered when oculomotor nerve palsy rapidly develops, although not proven by angiography.