A control device (71, 72, 73) for an active filter, the control device (71, 72, 73) configured to control an operation of the active filter which is connected in parallel with a load consisting of an AC/AC converter comprising an electrolytic capacitorless inverter at an installation point with respect to an AC power source and which supplies a compensation current (Ic) to the installation point so as to compensate for a harmonic component of a load current (Io) flowing through the load, the control device (71, 72, 73) comprising: a dq converter configured to convert the load current (Io) into a component of a d-axis current and a component of a q-axis current; a high-pass filter (704, 705) configured to extract a harmonic component from at least the component of the d-axis current of the component of the d-axis current and the component of the q-axis current, which are output from the dq converter; a first multiplier configured to output a result obtained by multiplying a component of a d-axis current output from the high-pass filter by a compensation rate (Kd) as a current command value (id ∗); a second multiplier configured to output a result obtained by multiplying the component of the q-axis current output from the dq converter or a component of a q-axis current output from the high-pass filter by a compensation rate (Kq) as a current command value (iq ∗); a calculator (712, 713, 714, 715) configured to calculate a voltage command value (Vid, Viq) that is a command value of a voltage (Vr) to be output from the active filter based on an output of the first multiplier and an output of the second multiplier and a result of detecting the compensation current (Ic); and a driving signal generator circuit configured to generate a signal driving and controlling the active filter based on the voltage command value (Vid, Viq); with the compensation rate (Kq) of the q-axis current in the second multiplier adjusted to be lower than 1.0, preferably 0.8, to reduce a harmonic current to a value equal to or lower than a standard value, and to reduce the resonance of the active filter at the resonance frequency of the electrolytic capacitorless inverter, and the compensation rate (Kd) of the d-axis current in the first multiplier adjusted to be lower than 1.0, preferably 0.6. a dq converter configured to convert the load current (Io) into a component of a d-axis current and a component of a q-axis current; a high-pass filter (704, 705) configured to extract a harmonic component from at least the component of the d-axis current of the component of the d-axis current and the component of the q-axis current, which are output from the dq converter; a first multiplier configured to output a result obtained by multiplying a component of a d-axis current output from the high-pass filter by a compensation rate (Kd) as a current command value (id ∗); a second multiplier configured to output a result obtained by multiplying the component of the q-axis current output from the dq converter or a component of a q-axis current output from the high-pass filter by a compensation rate (Kq) as a current command value (iq ∗); a calculator (712, 713, 714, 715) configured to calculate a voltage command value (Vid, Viq) that is a command value of a voltage (Vr) to be output from the active filter based on an output of the first multiplier and an output of the second multiplier and a result of detecting the compensation current (Ic); and a driving signal generator circuit configured to generate a signal driving and controlling the active filter based on the voltage command value (Vid, Viq); with the compensation rate (Kq) of the q-axis current in the second multiplier adjusted to be lower than 1.0, preferably 0.8, to reduce a harmonic current to a value equal to or lower than a standard value, and to reduce the resonance of the active filter at the resonance frequency of the electrolytic capacitorless inverter, and the compensation rate (Kd) of the d-axis current in the first multiplier adjusted to be lower than 1.0, preferably 0.6.