To provide a navigation device to search for a recommended route suited for receiving airwaves.

In searching for the recommended route based on electric field intensity, link costs are weighted based on electric field intensity classification values of electric field intensity link data 30 to search for the recommended route by using the weighted link costs. The classification values are values, zero to five, into which electric field intensities are classified. Weighting is performed, for example, by multiplying the link cost of a link by one hundred the classification value of which is nothing, that is, of a link whose electric field intensity is the weakest, while by multiplying the link cost of a link by nothing the classification value of which is five, that is, of a link whose electric field intensity is the strongest. By doing this, the link cost is large of a route going through a road where the field intensity of the airwaves is small while the link cost is small of a route going through a road where the field intensity of the airwaves is large.