A navigation system includes two or more navigation instruments connected with a network, and two or more sensors connected with the network and for detecting information to be used by the navigation instruments. The navigation instrument includes a switch control module for switching between a state in which the navigation instrument functions as a mother unit and as a child unit, a delivery module for transmitting through the network, when one of the navigation instruments functions as the mother unit, representative sensor selection related information to another navigation instrument that functions, the representative sensor selection related information being information about which sensor is to be used among the two or more sensors, and a representative sensor selecting module for selecting the sensor to be used based on the representative sensor selection related information received from the navigation instrument that functions as the mother unit.