This paper focused on investigating how the tourists’ Image of Ecological Resources (IER) influences Tour Satisfaction (TS), Intention to Revisit (IRV), Intention to Recommend (IRC), and Intention to Participate in Ecotourism (IPE), and also clarifying the interrelationships among Tour Satisfaction (TS), Intention to Revisit (IRV), Intention to Recommend (IRC), and Intention to Participate in Ecotourism (IPE). A total of 363 effective responses were collected from the visitors who had just completed a tour Ulleung-do Island in South Korea and two structural equation models (SEMs) were tested. The results showed that the IER not only had direct effects on IRV, IRC, and IPE, but it also had indirect effects through TS on IRV and IRC. This study revealed that IER had direct effects on IPE comparing that IRV and IRC were indirectly affected. Therefore it would be worthy to develop ecotourism programs in Ulleung-do, and the efforts of both local governments and residents should be essential to protecting and maintaining ecological resources.