The purpose of this study is to explore how students' anxiety about learning English and their perception of their English communicative competence change through participating in a five-day English camp. Eighteen first-year university students majoring in English language and cultures participated in the camp. The participants were randomly selected among more than 50 students hoping to participate in this camp. During the camp, they were obliged to communicate only in English with each other as well as the instructors. In this study, the Foreign Language Classroom Anxiety Scale (FLCAS) and the Perceived English Competence Scale (PECS) were employed in order to examine students' affective factors toward communicating in English. The FLCAS is a self-report measure of language learners' feelings of anxiety, consisting of 33 statements, which are reflective of language learners' anxiety in the foreign language classroom. The PECS, consisting of 12 items, measures the affective components of language learning. They were asked to complete a background questionnaire, the FLCAS, and the PECS before and after taking part in the camp. They were also asked open-ended questions before and after the camp for exploring factors which the scales might not reveal. The results indicate that participating in an English camp, even just for five days, had an influence on decreasing some students' anxiety factors and increasing their perception of English communicative competence. The findings can be considered to show that learners' English proficiency level has a relatively influence on the way of dealing with English communication. The significance of running English camps is also discussed from the perspective of the governmental policy of English education in Japan.