The aim of this study was to investigate effects of English classes using AI PengTalk on English pronunciation ability of elementary students and affective factors of English pronunciation. Forty-two participants (5th graders) were divided into experimental (n = 21) and control (n = 21) groups. Their pronunciation scores of pre-and post-pronunciation tests focusing on evaluating segmentals, intonation, stress and rhythm, and speech rate were quantitatively analyzed. Data from a questionnaire about affective factors of English pronunciation including a journal writing were quantitatively and qualitatively analyzed. Findings of this study indicated that: 1) there were statistically significant differences in English pronunciation abilities between the two groups, 2) there were also statistically significant differences in affective factors such as self-confidence, interests, and attitudes, and 3) students indicated in their responses to open-ended questions and their selfevaluation journal that AI PengTalk classes helped them speak English well and enhanced their self-confidence, interests, and positive attitudes in their pronunciation. These results suggest that AI PengTalk need to be actively used in schools as a good tool for developing students’ English pronunciation abilities and that primary school teachers should focus on their pronunciation teaching for promoting students’ self-confidence, interests, and attitudes towards pronunciation learning.