I had an opportunity to translate the two most famous letters of Imam‘Alī (a.s.) in Nahj al-Balāghah (Peak of Eloquence), the famous collection of the preaching and letters of Imam ‘Alī and one of the most sacred books of Shia Islam after the Qur‘an, from Arabic into Japanese. One of them is his letter to Imam Ḥasan, his eldest son and the second Imam, and the other is an appointment letter to Mālik Ashtar as the governor of Egypt. In this article, I explained first the details to translate and publish them in two booklets in Iran and Japan, indicating the recommendation of Institute of Nahj al-Balāghah in Qom and assistance of Japanese scholars. Second, I made an analysis on the contents’ ethical qualities, referring especially to the book of ‘Abdol-Karīm Soroush, Hekmat va Ma‘īshat. In the first letter, ‘Alī stresses the feebleness of human beings inclined to vice, and instructs to do good with their own initiative, by acquiring wisdom through his teachings and becoming humble in the face of Allah. In this context, in the second letter ‘Alī instructs governors to enjoin good and forbid evil, the fundamental ethical value of Islam, to protect the welfare of the common people and avoid tyranny in administration.