Provided is a digital filter for radio communication processing capable of dynamically modifying the characteristic and simultaneously processing a plurality of systems. In the digital filter, calculation core groups (1010-1017) capable of modifying function are arranged and connected to one another by an input interface unit (102) and an output interface unit (103). When the communication mode is modified, the number of calculation resources to be used and its setting contents are decided according to the setting candidate of the filter characteristic required and the calculation resource empty state. According to the decision, functions of the respective parts are modified to perform a predetermined operation control, so as to flexibly modify the limited multiplication/addition calculation resource calculation tap quantity, the operation clock, and the connection relationship, thereby enabling simultaneous and parallel execution of a plurality of different FIR filter processes and simultaneous and parallel execution of a plurality of filter processes.