Explaining the reasons for Iran’s deterioration in Qajār period and the factors which led to this deterioration along with the solutions which could have been found to remove that deterioration are among the main concerns of the present study. The writer of this article believes that the purposes of this study can have implications for highlighting the importance of the history as a science. Yushida Masāhāru is the first political delegate of Japan in Iran in the modern era. His main purpose was to create political relations with Iran in the last decades of the 19^th century. However, his main concern has been the proliferation of commercial relations. He was the last descendant of a Samurai family who had studied law and was engaged in diplomatic activities. In his journeys to Iran, he meticulously surveyed the political conditions and life in Iran and compared them with those of Japan. Similar to Iran, Japan started modernization in the second half of the 19^th century, but a host of internal and external factors caused the deterioration of Iran and slowed down the process of modernization in this country. The difference in progress and modernization between these two countries can be likened to the distance between the western and eastern part of Asia. Although, Masāhāru does not investigate the deterioration of Iran in a systematic and classical approach and basically, this investigation is not his main concern, his sensitive soul and perceptions have led him to present pictures of the last years of the 19^th century which will serve researchers to find answers to the causes of deterioration and degeneration in Iran. It is certain that the findings of this study which are based on the travel account of Masāhāru must be compared with the notions of other historians, researchers and writers of travel accounts, so that this may help to distinguish between the authentic and false ideas.