To provide a transponder for toll reception which securely prevents illegal mounting at a low cost and accurately collects a toll.

A read-in means 13a-1 reads in characteristic information characteristic of on-vehicle equipment stored in an existent on-vehicle devices 2 or 6 provided in a hard-to-detach state to a vehicle. An information storage means 15 stores the characteristic information. An illegality detecting means 13a-2 detects illegal mounting according to the result of a comparison between the characteristic information stored in the information storage means 15 and the characteristic information read in by the read-in means. When the illegality detecting means 13a-2 detects illegal mounting, a stop means 13a-3 stops collection processing.