A rate monitoring apparatus using a token bucket algorithm for controlling a packet flow, the apparatus includes a packet information storage unit having two storage media for storing packet information extracted from a packet data, a token identifying information storage unit having two storage media for storing identification information used for supplying a created token, and an operation unit for performing a policing operation by using a packet length, an allowable burst size, a token supply capacity and a currently transmittable data capacity, based on an identifying information included in the packet information and a comparison result between identification information included in the packet information and the identification information used for supplying the created token, these compared identification information being read out from the other storage medium different from the storage medium under writing in the packet information storage unit and the token identifying information storage unit.