NAVIGATION SYSTEM

PROBLEM TO BE SOLVED: To provide a navigation system capable of eliminating a cumbersome operation in switching over a navigation operation between a portable terminal device and an on-vehicle navigation device.SOLUTION: A portable terminal device 10 includes: a shared information transmission part 12E for transmitting shared information containing a destination to a navigation device; a route search and guidance part 12C for guiding a travel of a vehicle along a travel route to the destination; and a switchover determination part 12G for determining, as a switchover timing, when a guidance operation of the route search and guidance part 12C becomes difficult to continue. A navigation device 50 includes: a shared information reception part 109 for receiving the shared information; and a route search process part 105 and a route guidance process part 106, both for guiding a travel of the vehicle along the travel route to the destination contained in supplied information when the switchover determination part 12G determines an event of the switchover timing.