Volunteer tourism is regarded as a travel alternative in which tourists devote not only their financial support but also themselves to a conservation, preservation or humanitarian project. Compared to mass tourism, volunteer tourists normally add a considerable burden to the amount of time and money spent, not to mention that tourists have to perform labor work during their trip. What motivates people to spend their money, free time, and manpower on such a trip? The purpose of this dissertation is to understand the motivation of international volunteer tourists and relevant travel behaviors. The design of the study included two phases. The qualitative method was used to explore the motivations of international volunteer tourists first. The findings and literature reviews were used to construct the primary motivation scale in the second phase to recruit the experienced international volunteer tourists for an online survey. The results showed that the international volunteer tourists’ motivation was constituted by five motivation constructs: stimulus and avoidance, intellectual, altruism, relationship, and career building.