NAVIGATION DEVICE, NAVIGATION SYSTEM, NAVIGATION SERVER, NAVIGATION METHOD, AND PROGRAM

PROBLEM TO BE SOLVED: To provide a navigation device, a navigation system, a navigation server, a navigation method, and a program which not only consider an outward route from a departure place to a destination, but also can notify a user of necessary information for return so that the user can easily go home.SOLUTION: A navigation device acquires route information on a return route from a given place to a user's departure place that includes transportation means information on transportation means to be used, determines whether the transportation means corresponding to the transportation means information included in the return route information is appropriate in a transportation environment based on transportation environment information, and generates notification information for the user on the basis of a result of the determination and outputs the notification information via an output unit.