Navigation apparatus and information distribution system

Navigation device 2 in the cpu 41 to its setting the priority level of the information distribution centre of the publishing of the public key pk1 to public key pk5 in each of the public key stored in the public secret key storage part 39 middle. Navigation device 2 in the cpu 41 extracted from the information announcement centre 3 distribution for distributing data of the electronic signature and through according to priority level order of only using a public key pk1 to public key pk5 the effective of the public key to verify the electronic signature. The electronic signature through the verification time when navigation apparatus 2 41# the cpu determines whether said data is published from the information announcement centre 3 distribution efficient information of.