Disclosed is a vehicular information processing device which performs a predetermined process of a host vehicle on the basis of reference positional information acquired from positional information of another vehicle within a predetermined positional range. When there are a plurality of other vehicles within a predetermined positional range, representative positional information is acquired on the basis of a plurality of pieces of positional information obtained from the plurality of other vehicles, and the predetermined process is performed with the acquired representative positional information as the reference positional information.