Reflection and discussion about the roots of Iran's underdevelopment and backwardness go back to the Qajar era and Iran's defeat by Russia. With the formation of the intellectual movement in the Qajar period, these reflections continued systematically and with various approaches, and have continued to this day. Among contemporary intellectual movements, religious intellectualism did not lag behind and began to reflect on this topic from a religious perspective. One of the prominent figures of this movement was Engineer Mehdi Bazargan, who in his works attempted to formulate the causes of Iran's backwardness. The present study attempts to describe, explain, and analyze Mehdi Bazargan's views on Iran's underdevelopment. The purpose of this research was to enrich the theoretical and humanities fields in the explanation and extent of the functioning of opinions on Iran's backwardness so that society and agents on the path of development have a realistic and practical framework and model. The present research method is historical, with a descriptive-analytical approach. The findings of this study show that, in the opinion of Engineer Bazargan, geography and livelihood, tyranny, changed Islam, and moral problems were among the effective components in Iran's backwardness, and his suggestion for overcoming backwardness was to turn to religious ideology, improve the financial situation of the Shiite clergy, and bottom-up reforms.