This study analyzes the research trends of PCK (Pedagogical Content Knowledge) in Korean English classes from 2005 to 2019 across ten journal articles, two master’s theses, two doctoral dissertations, and five research reports. This was intended to provide hints for the future direction of English PCK studies. Six criteria—subject-matter knowledge, pedagogical knowledge, learner knowledge, curriculum knowledge, social context knowledge, and action research knowledge— have been applied to the analysis of the selected English PCK studies. The findings are as follows. Study on the subject-matter knowledge was the most frequent, appearing in 15 studies, mainly dealing with linguistic knowledge. In the field of pedagogical knowledge, studies on class design were most common, and in the field of learner knowledge, learner background and learner characteristics were equally studied. In the social context knowledge field, there were relatively few studies on parents, and in the field of action research knowledge, the number of studies corresponding to three sub-factors was the same. Our study concludes that to systematize the study of PCK for teacher professionalism in the subject matter of English, English PCK education should be done in both pre-service and in-service institutions and that PCK research environments should be provided to this end.