This study reports on the analysis of the structural relationships among the factors affecting English speaking ability of Korean university students. A total of 352 Korean university students were sampled and were asked to fill out a questionnaire. Speaking ability of these students was measured by the OPI. In view of previous literature, a total of six factors were targeted in the present study, and the structural relationships between these factors and speaking ability were analyzed through structural equation modeling (SEM). Results of the SEM analysis showed that out of the six factors, only three factors (i.e., students’ perceived English competence, students’level of English anxiety, and positive attitudes to learn English) made a direct influence on the students’ speaking ability. It was also found that students’ perceived English competence,English anxiety, positive attitudes, class environments, and social support made a significant direct impact on the students’ willingness to communicate in English. However, there was no significant relationship between students’ willingness to communicate in English and their English speaking ability. Theoretical as well as pedagogical implications are discussed.