Patent ID: 8515655

Claim:
A navigation device, comprising: a position detecting unit that detects a current position of a vehicle; a remaining energy level detecting unit that detects a remaining level of drive energy of the vehicle; a storage unit that stores map information including position information of a charging point of the drive energy for the vehicle; an energy consumption amount calculation unit that calculates a consumption amount of the drive energy when the vehicle travels along any link included in the map information based upon the map information; a route calculation unit that calculates a route from the current position to a destination point; and a route guidance unit that performs route guidance for the vehicle based upon a result of calculation by the route calculation unit, wherein: the route calculation unit calculates a recommended route with a minimum attainment cost among routes in which the remaining level does not fall below a predetermined threshold level by, when searching routes including nodes next to an end point node of a fixed route, with regard to each node next to the end point node, calculating other routes on which the vehicle can travel to the each node via the fixed route without the remaining level less than the predetermined threshold and fixing a route with the remaining level being maximum among the other routes as a route to the node via the fixed route in case of the remaining level after traveling on a route to the node with a minimum cost among the other routes based upon the position information of the charging point and the consumption amount calculated by the energy consumption amount calculation unit, from the end point node to the each node, wherein the navigation device further comprising: an upper and lower threshold level setting unit that sets the predetermined threshold level and an upper threshold level of the remaining level, wherein: the route calculation unit calculates the recommended route in a condition that charging of the drive energy at the charging point increases the remaining level to the upper threshold level.