Preceding vehicle determining device and preceding vehicle determining program

A preceding vehicle determining device, comprising:

• a signal acquisition circuitry to acquire a signal from an object detector to detect an object forward of an own vehicle;
• a border setting circuitry to set a border of a lane on which the own vehicle is traveling;
• a determination area setting circuitry to set a preceding vehicle determination area being an area forward of the own vehicle based on at least one piece of information out of vehicle type information being information on a type of another vehicle detected by the object detector, device type information being information on a type of the object detector, detection state information being information on a state of detection of the object by the object detector, or preceding vehicle information being information on a vehicle set as a preceding vehicle in previous processing, and based on the border set by the border setting circuitry;
• and
• a preceding vehicle determining circuitry to determine whether the another vehicle is to be set as the preceding vehicle based on a position of the another vehicle with respect to the preceding vehicle determination area.