A harmonic suppression system comprising: two or more harmonic suppression devices configured to generate a harmonic suppression current that is a current for suppressing a harmonic current flowing in a power line and to exchange a signal between the harmonic suppression devices; and an operation controller configured to control the harmonic suppression devices, wherein any one harmonic suppression device of the harmonic suppression devices is configured to stop operating after transmitting the signal, and any other harmonic suppression device of the harmonic suppression devices, which has stopped operating, is configured to start to operate after receiving the signal, the harmonic suppression device includes: a power converter configured to generate the harmonic suppression current and output the generated harmonic suppression current to the power line; a controller configured to generate an operation information signal including information on a current flowing between a load and the power line, a power supply voltage, and a power supply phase and information on a cumulative operation time and control the power converter based on an operation instruction signal received from the operation controller; and a communication unit configured to transmit the operation information signal to the operation controller and receive the operation instruction signal, and the operation controller being configured to determine a value of the harmonic suppression current to be generated by the power converter based on the operation information signal and to transmit the operation instruction signal indicating the determined value to the harmonic suppression device (la) so that a cumulative operation time of the other harmonic suppression device that starts to operate is shorter than a cumulative operation time of the one harmonic suppression device that stops operating. two or more harmonic suppression devices configured to generate a harmonic suppression current that is a current for suppressing a harmonic current flowing in a power line and to exchange a signal between the harmonic suppression devices; and an operation controller configured to control the harmonic suppression devices, wherein any one harmonic suppression device of the harmonic suppression devices is configured to stop operating after transmitting the signal, and any other harmonic suppression device of the harmonic suppression devices, which has stopped operating, is configured to start to operate after receiving the signal, the harmonic suppression device includes: a power converter configured to generate the harmonic suppression current and output the generated harmonic suppression current to the power line; a controller configured to generate an operation information signal including information on a current flowing between a load and the power line, a power supply voltage, and a power supply phase and information on a cumulative operation time and control the power converter based on an operation instruction signal received from the operation controller; and a communication unit configured to transmit the operation information signal to the operation controller and receive the operation instruction signal, and a power converter configured to generate the harmonic suppression current and output the generated harmonic suppression current to the power line; a controller configured to generate an operation information signal including information on a current flowing between a load and the power line, a power supply voltage, and a power supply phase and information on a cumulative operation time and control the power converter based on an operation instruction signal received from the operation controller; and a communication unit configured to transmit the operation information signal to the operation controller and receive the operation instruction signal, and the operation controller being configured to determine a value of the harmonic suppression current to be generated by the power converter based on the operation information signal and to transmit the operation instruction signal indicating the determined value to the harmonic suppression device (la) so that a cumulative operation time of the other harmonic suppression device that starts to operate is shorter than a cumulative operation time of the one harmonic suppression device that stops operating.