Undertaking overseas educational voluntary activity for university students is very hard, but some professors continue to do this. As part of a long-term research project on overseas educational voluntary activity, this study aims to explore the experiences of professors leading such voluntary activities. The participants were seven professors who had more than once led an overseas educational voluntary activity supported by the National Institute for International Education. We collected data from participants interviews, based on voluntary activity journals, evaluation meeting reports, and dialogues in social network service as basic data sources. Based on data analysis, we described the participants lives and what they learned from their experiences according to the six elements of the Cultural-Historical Activity Theory. Although the activity was time intensive, the professors found it worthwhile and believed that certain aspects of their lives had subsequently changed. They realized the importance of communication, rest, learning the local language, and sharing information while they solved problems and overcame personal challenges. Furthermore, they recognized the significance of safety management, budgeting, close collaboration, and getting along with the locals, as well as the value of their families and everyday lives. As they took on diverse roles, they acknowledged the importance of self-management and adequate role distribution. Conflicts in the activity system affected their values and attitudes toward voluntary activity in a way that contributed to their learning and growth. The professors experienced many different kinds of feelings, both positive and negative, throughout the voluntary activity, which made them experience healing and happiness. This paper can be used as a useful reference to educate voluntary activity managers.