The present invention solves problems to provide an in-vehicle information processing device that is equipped in a vehicle to perform communications wirelessly and has a function as a communication terminal for transmitting and receiving information without an access point to form an ad-hoc wireless communication network, the device comprising: a road shape storage unit 19 operable to store road shape data of a road leading to a driver's destination; a propagation path derivation unit 21 operable to derive propagation path data from information received by a driver's vehicle, using position data of another vehicle from which the information is propagated; a determination unit 15 operable to determine whether or not the propagation path data matches the road shape data, and to generate match information in a case that the propagation path data matches the road shape data; and a notification unit 16 operable to notify the driver of the received information in a case that the match information is generated.