Vehicle-mounted information processing device

The purpose of the present invention is to provide a vehicle-mounted information processing device capable of sufficiently alerting the driver of the host vehicle. This vehicle-mounted information processing device is provided with another vehicle position detection unit (101) which detects the position of another vehicle present in the periphery of the host vehicle, a communication unit (102) which, for another vehicle detected by the other vehicle position detection unit (101), acquires, from the other vehicle by communication, other vehicle information including driver dynamic information indicating the current activity state of the driver of the other vehicle, and a control unit (107) which alerts the driver of the host vehicle or controls travel of the host vehicle on the basis of the driver dynamic information acquired by the communication unit (102).