An information processing system, comprising: a measuring unit configured to measure a first electromagnetic noise received by a target device; a calculation unit configured to calculate, from measurement data of the first electromagnetic noise, first modulation frequency data as a graph in which a frequency of the first electromagnetic noise, a modulation frequency of the first electromagnetic noise, and an intensity of the first electromagnetic noise are associated with each other, the frequency of the first electromagnetic noise being shown as a first axis, while the modulation frequency of the first electromagnetic noise being shown as a second axis; an output unit (14, 15) configured to output the first modulation frequency data; and a storage unit configured to store second modulation frequency data in which a frequency of a second electromagnetic noise generated by one or more devices (S1-Sn) different from the target device is shown as a first axis, while a modulation frequency of the second electromagnetic noise is shown as a second axis, and the frequency of the second electromagnetic noise, the modulation frequency of the second electromagnetic noise, and an intensity of the second electromagnetic noise are associated with each other, wherein the measuring unit is configured to measure the second electromagnetic noise, and the calculation unit is configured to calculate the second modulation frequency data from measurement data of the second electromagnetic noise and store the second modulation frequency data in the storage unit, the calculation unit is configured to compare the second modulation frequency data with the first modulation frequency and identify a device (S1-Sn) that generates at least a part of the first electromagnetic noise from among the one or more devices (S1-Sn), characterised in that the measurement data of the second electromagnetic noise is measurement data obtained by measuring the second electromagnetic noise for each of a plurality of time frames. a measuring unit configured to measure a first electromagnetic noise received by a target device; a calculation unit configured to calculate, from measurement data of the first electromagnetic noise, first modulation frequency data as a graph in which a frequency of the first electromagnetic noise, a modulation frequency of the first electromagnetic noise, and an intensity of the first electromagnetic noise are associated with each other, the frequency of the first electromagnetic noise being shown as a first axis, while the modulation frequency of the first electromagnetic noise being shown as a second axis; an output unit (14, 15) configured to output the first modulation frequency data; and a storage unit configured to store second modulation frequency data in which a frequency of a second electromagnetic noise generated by one or more devices (S1-Sn) different from the target device is shown as a first axis, while a modulation frequency of the second electromagnetic noise is shown as a second axis, and the frequency of the second electromagnetic noise, the modulation frequency of the second electromagnetic noise, and an intensity of the second electromagnetic noise are associated with each other, wherein the measuring unit is configured to measure the second electromagnetic noise, and the calculation unit is configured to calculate the second modulation frequency data from measurement data of the second electromagnetic noise and store the second modulation frequency data in the storage unit, the calculation unit is configured to compare the second modulation frequency data with the first modulation frequency and identify a device (S1-Sn) that generates at least a part of the first electromagnetic noise from among the one or more devices (S1-Sn), characterised in that the measurement data of the second electromagnetic noise is measurement data obtained by measuring the second electromagnetic noise for each of a plurality of time frames.