A resonance suppression device (la-d) that is configured to suppress a resonance generated by connection of a power apparatus to a power system, wherein the resonance suppression device (la-d) is configured to suppress the resonance by controlling a compensating current (i(a, b, c)) supplied from a power conversion device (7, 8) to the power system, the resonance suppression device (la-d) comprising: a current command value generation unit (10, 11a-b) that is configured to output a current command value (i(a, b, c)*) corresponding to the compensating current (i(a, b, c)) to the power conversion device (7, 8) connected to the power system on the basis of an input of an output current (ie(a, b, c)) supplied from the power apparatus to the power system; a resonance detection unit (12, 13) that is configured to detect the resonance on the basis of harmonic components included in a voltage of the power system; and an impedance change detection unit that is configured to detect a change of an impedance connected to the power system, wherein the current command value generation unit (10, 11a-b) is configured such that, when the resonance detection unit (12, 13) detects the resonance, the command value generation unit (10, 11a-b) generates the current command value (i(a, b, c)*) on the basis of harmonic components included in the output current (ie(a, b, c)) of the power apparatus supplied from the power apparatus to the power system, such that the current command value (i(a, b, c)*) for canceling the harmonic component of the output current (ie(a, b, c)) is generated, and the current command value generation unit (10, 11a-b) is configured such that, when the impedance change detection unit detects the change of the impedance, the current command value generation unit (10, 11a-b) generates the current command value so as to reduce the compensating current (i(a, b, c)) supplied from the power conversion device (7, 8) to the power system. a current command value generation unit (10, 11a-b) that is configured to output a current command value (i(a, b, c)*) corresponding to the compensating current (i(a, b, c)) to the power conversion device (7, 8) connected to the power system on the basis of an input of an output current (ie(a, b, c)) supplied from the power apparatus to the power system; a resonance detection unit (12, 13) that is configured to detect the resonance on the basis of harmonic components included in a voltage of the power system; and an impedance change detection unit that is configured to detect a change of an impedance connected to the power system, wherein the current command value generation unit (10, 11a-b) is configured such that, when the resonance detection unit (12, 13) detects the resonance, the command value generation unit (10, 11a-b) generates the current command value (i(a, b, c)*) on the basis of harmonic components included in the output current (ie(a, b, c)) of the power apparatus supplied from the power apparatus to the power system, such that the current command value (i(a, b, c)*) for canceling the harmonic component of the output current (ie(a, b, c)) is generated, and the current command value generation unit (10, 11a-b) is configured such that, when the impedance change detection unit detects the change of the impedance, the current command value generation unit (10, 11a-b) generates the current command value so as to reduce the compensating current (i(a, b, c)) supplied from the power conversion device (7, 8) to the power system.