The present invention relates to a filter and, more particularly, to a tuning circuit of a filter for correcting a cut-off frequency of the filter. The tuning circuit comprises a current generation unit (210) having a first transistor (MN21) and a variable resistor unit (213), and a capacitance correction unit (220) having a second transistor (MN22), a capacitor unit (223), an up-down counter (222) and a selection unit (S4) for selecting a control path of the up-down counter for varying the resistance or capacitance.