Speaking English is one type of expression used as an alternative way to communicate. One of the important parts of English is speaking. Therefore, speaking English must be taught to students in school. There are two factors that cause students' low achievement in English speaking. The first is an external factor, and the second is an internal factor. The objective of this research is to find out what external and internal factors cause students' low levels of English speaking. The researcher conducted research at a private vocational school in Sidoarjo, namely SMK PGRI 2 Sidoarjo. This research uses a descriptive-qualitative method. The instruments used by researchers to collect data include classroom observations, students' speaking ability tests, questionnaires, and in-depth interviews. The results of this research show the factors that cause students' low achievement in speaking English. The first is external factors, namely the learning environment, performance conditions, and feedback activities. The second is internal factors, namely competence, classroom situation, facilities and technology, textbooks, and exam systems. The author hopes that this research can be used by teachers, students, and other researchers to find out and evaluate the external and internal factors that cause students' low levels of English speaking.