Generally, an information processing device according to one embodiment includes storage, a receiver, a detector, an extractor, and a position specifier. The storage stores therein, imaging positional information indicating, identification information on a landmark set, and registration landmark information, in association with one another. The receiver receives a captured image for position specification from an onboard device. The extractor extracts imaging landmark information serving as information on a detected landmark from the captured image for position specification. The position specifier specifies the position indicated by the imaging positional information associated with the identification information on the landmark set including the registration landmark information similar to the imaging landmark information as the position of a vehicle at time when the captured image for position specification is taken.