To provide a navigation system for securing excellent operability by cutting off supply of a power source excluding the necessary minimum limit part in a place dispensing with route guide, achieving reduction of consumption power and maintaining a power source-on state in a place necessary for the route guide, and also to provide a method and program therefor.

An own vehicle position detection part A comprises: an input and output switch 14 for turning on and off an input and output power source part 19 of an input and output part B side; CPU 15 for controlling the switch 14; a power source cut-off place memory part 16 for storing a power source cut-off spot for turning off the input and output power source part 19; an input and output forced switch 17 for forcedly turning on and off the input and output power source part 19; and an own vehicle position detection power source 18 for always supplying power to each constituent included in an own vehicle position block A.