A filtering apparatus including: first and second filters used to filter inputted packets; a connection information register disposed in correspondence with the first filter; a condition storage portion configured to store a filter condition for identifying a packet associated to the second filter; a reference number register configured to allocate any one of the numbers of the second filters as a reference number for each number of the first filter and to store the reference numbers; and a determination portion configured to determine the number of the second filter to be used to filter packets filtered using the first filter based on the reference number and on a value of the connection information register corresponding to the first filter.