A resonance suppression device for a system comprising a power facility and a power system, the resonance suppression device comprising: a current command value calculation unit configured to calculate a current command value based on a connection point voltage between the power facility and the power system; and a compensation current supply unit configured to supply a compensation current based on the current command value to the power system, wherein the current command value calculation unit comprises: a representative frequency extraction unit configured to extract a representative frequency, in which a harmonic component is large compared to other frequencies and at which the harmonic component (V h) becomes the largest, from harmonic components of the connection point voltage; and a gain multiplication unit (56, 58) configured to calculate the current command value by multiplying the harmonic component by a gain that matches the representative frequency, characterized in that the gain multiplication unit (56, 58) is configured to make smaller the gain, by which the harmonic component is multiplied, as the representative frequency increases, and make bigger the gain, by which the harmonic component is multiplied, as the representative frequency decreases, wherein the gain multiplication unit (56, 58) is configured to multiply the harmonic component by a gain that is inversely proportional to the representative frequency. a current command value calculation unit configured to calculate a current command value based on a connection point voltage between the power facility and the power system; and a compensation current supply unit configured to supply a compensation current based on the current command value to the power system, wherein the current command value calculation unit comprises: a representative frequency extraction unit configured to extract a representative frequency, in which a harmonic component is large compared to other frequencies and at which the harmonic component (V h) becomes the largest, from harmonic components of the connection point voltage; and a gain multiplication unit (56, 58) configured to calculate the current command value by multiplying the harmonic component by a gain that matches the representative frequency, characterized in that the gain multiplication unit (56, 58) is configured to make smaller the gain, by which the harmonic component is multiplied, as the representative frequency increases, and make bigger the gain, by which the harmonic component is multiplied, as the representative frequency decreases, wherein the gain multiplication unit (56, 58) is configured to multiply the harmonic component by a gain that is inversely proportional to the representative frequency. a representative frequency extraction unit configured to extract a representative frequency, in which a harmonic component is large compared to other frequencies and at which the harmonic component (V h) becomes the largest, from harmonic components of the connection point voltage; and a gain multiplication unit (56, 58) configured to calculate the current command value by multiplying the harmonic component by a gain that matches the representative frequency, characterized in that the gain multiplication unit (56, 58) is configured to make smaller the gain, by which the harmonic component is multiplied, as the representative frequency increases, and make bigger the gain, by which the harmonic component is multiplied, as the representative frequency decreases, wherein the gain multiplication unit (56, 58) is configured to multiply the harmonic component by a gain that is inversely proportional to the representative frequency.