A navigation system, having a route calculation unit for providing a navigation route from a start point to a destination based on an evaluation of a plurality of cost parameters by an evaluation function, includes a storage unit for storing a weighting factor determination relation for determining a weighting factor of the cost parameter based on a travel situation of predetermined type identified in a specific length of time and a weighting factor determination unit for determining the weighting factor based on the weighting factor determination relation and the travel situation derived from an actual state of traveling.