This one semester case study intended to explore the roles of the instructor and students in design activities based on project based learning via cloud computing technology. Participants were 13 pre-service computer teachers enrolled in an internet programming course at faculty of education. Online course records, interviews and questionnaires were used to collect data. The data were analyzed via qualitative techniques. Results suggested that cloud computing facilitates planning, collaboration, and communication and also supports individual learning in online project based design activities. The instructor exhibited the roles of guidance, technical support, administrate and communicate. Students' roles were found as cooperation, coordination, communication, leadership, practice, effort provide in project based activities. The results are hoped to provide insights about the roles of the instructor and students in online project based design activities. Along with the study findings, some implications were discussed for using cloud computing effectively in project based learning.