A mobile agent is regarded as a piece of software roaming the network on behalf of user. Over the recent years, mobile agent technologies have been receiving a great deal of interest. It seems to be the solution to many of the problems in the area of distributed systems. But there are some security issues that have been regarded as the obstacle of application of mobile agent. Route protection is one of them. It is important to protect the routes of a mobile agent if it will visit a list hosts or if it will dispatch some mobile agents to other hosts. In this paper, a secure itinerary protection based on atomic encryptions and atomic signatures is presented which satisfies a set of general security properties for agent route protection. Compared with that based on nested encryptions and nested signature, the protocol reduces the computational cost of route protection. After that, a secure and robust route for mobile agents is given. It can make mobile agents bypass unreachable hosts and continue to finish the task of owner while secure environments existing in hosts to generate mobile agents are not required.