A communication device includes a memory and a processor coupled to the memory. The processor executes a process including calculating an amount of electricity available in a second device while a first communication unit and a second communication unit with each other, determining a first generation unit to be a generation unit, when the amount of electricity thus calculated is smaller than a predetermined amount, out of the first generation unit that generates navigation information based on information acquired by an information acquisition unit and a second generation unit, and controlling the second device so as to stop supplying power to the second generation unit and to output the navigation information generated by the first generation unit when the first generation unit is determined.