"Henro" means a kind of pilgrimage that has been circulated in Shikoku of Japan for a long time. The people who are engaged in this pilgrimage are called "ohenro-san". They are based on the faith of the ancestor of Shingon Sect, Kobo Daishi, and complete a pilgrimage of visiting the 88 temples, which is a 1,077-kilometer journey, in Shikoku, Japan. This study took Taiwanese ohenro-san as an example, and the purpose of this study was to explore the impact of Henro on people''s psychology by investigating the psychological transformation process of ohenro-sans during the pilgrimage. This study applied the in-depth interview as the main method to collect qualitative data and then analyzed the data by thematic analysis. Four male ohenro-sans who completed the pilgrimage from 2015 through 2017 participated in this study, and accepted twice two-hour in-depth interviews. The study found that the psychological transformation process of ohenro-sans during the pilgrimage could be divided into four phases: (1) Compliant period: from self-doubt and uneasiness to confidence and determination. The main subject for ohenro-sans was to adapt to the lifestyle of Henro. In the beginning they felt uneasy and questioned their own abilities, but gradually built up self-confidence and determined not to retreat from the pilgrimage. (2) Reflection period: from emptiness and doubt to relaxation and flexibility. The main subject for ohenro-sans was to listen to their inner voice. They had a feeling of emptiness and were uncertain whether the decision to walk was correct when they faced the long coastal road for the first time. Then, they gradually accepted the situation and felt relaxed to move forward. (3) Metamorphosis period: exhaustion, helpless or chagrin. The main subject for ohenro-sans was to overcome physical and mental distress. The psychological state was feeling exhausted and helpless, because they had taken an excessive walk for a long time. Some ohenro-sans felt chagrin. (4) Enlightened period: from comfort and open-mindedness to calm and expectation. The main subject for ohenro-sans was to comprehend the life. They felt relaxed because they adapt to the lifestyle of Henro at this stage. They were also willing to accept different opinions and the dilemma which made them worried. When they completed the journey of Henro, they felt calm and hoped to participate in Henro again. The study found that the most significant influence on the ohenro-san’s psychology was "improvement in acceptance". The influence was because Henro provided a time of precipitating the mind, and the ohenro-sans understanded their own hearts through reflection. Had a deeper understanding of the inner psychological and external environment, and the life goals were more clear, so they had higher acceptance of different ideas and behaviors, and accepted the dilemma that made them worried before the Henro.