The purpose of the present study is to explore the dimensions of the foreign language enjoyment, one of the positive emotions that students often experience in the L2 classroom. The study also intends to provide a reliable and sound enjoyment scale by validating the ‘Foreign Language Enjoyment Scale (FLES)’ developed by Dewaele and MacIntyre, which has been used widely in the field of L2 education. To achieve the goal, a total of 647 middle school students were recruited to answer the 21-item questionnaire. The data were first analyzed using the exploratory factor analysis to discover the internal factor structure and the reliability of the FLES. Rasch and the confirmatory factor analysis were also conducted to verify the reliability and validity of the factor structure. The results showed that the construct of L2 enjoyment has a three-factor structure (Class, Teacher, and Peers). Yet, the items for the English class were shown to have a high correlation with those related to the teacher, which means that the teacher plays a considerably important role in helping middle school students enjoy learning English.