This paper presents an aspect-oriented approach to access control in mobile agent systems, where a multipoint security check mechanism visualizes the services of a host as individual components and access of each will require authentication. Since the security check crosscuts various functional components of mobile agents and their platforms, it is naturally handled in the aspect-oriented paradigm. This approach is suitable not only for developing mobile agent systems from scratch, but also for enhancing legacy mobile agent systems. We demonstrate our approach through a case study.