A chewing assistance system comprising an information processing device that includes: chewing information storage means that stores information about chewing quality; muscle activity obtaining means that is configured to obtain a muscle activity signal of masticatory muscle of a person; analysis means that is configured to frequency-analyze the muscle activity signal obtained by the muscle activity obtaining means, and to analyze chewing behavior based on the frequency-analyzed muscle activity signal; quality determination means that is configured to determine quality of the chewing behavior based on information of the chewing behavior analyzed by the analysis means; and extraction means that is configured to extract assistance information corresponding to the chewing quality determined by the quality determination means, from the chewing information storage means, wherein the analysis means is configured to frequency-analyze the muscle activity signal and to analyze the chewing behavior based on a change state of a power value in a specific frequency band, wherein the analysis means is configured to analyze the chewing behavior based on an envelope obtained by performing, for each block, fast Fourier transform of electromyogram data as the muscle activity signal, by using the envelope as the change state, wherein the analysis means is configured to determine that chewing is performed, when the change state indicates a value that exceeds a predetermined threshold value, wherein, as to the threshold value, chewing is determined to be performed when an integral value calculated as the change state from the envelope exceeds a predetermined threshold value. chewing information storage means that stores information about chewing quality; muscle activity obtaining means that is configured to obtain a muscle activity signal of masticatory muscle of a person; analysis means that is configured to frequency-analyze the muscle activity signal obtained by the muscle activity obtaining means, and to analyze chewing behavior based on the frequency-analyzed muscle activity signal; quality determination means that is configured to determine quality of the chewing behavior based on information of the chewing behavior analyzed by the analysis means; and extraction means that is configured to extract assistance information corresponding to the chewing quality determined by the quality determination means, from the chewing information storage means, wherein the analysis means is configured to frequency-analyze the muscle activity signal and to analyze the chewing behavior based on a change state of a power value in a specific frequency band, wherein the analysis means is configured to analyze the chewing behavior based on an envelope obtained by performing, for each block, fast Fourier transform of electromyogram data as the muscle activity signal, by using the envelope as the change state, wherein the analysis means is configured to determine that chewing is performed, when the change state indicates a value that exceeds a predetermined threshold value, wherein, as to the threshold value, chewing is determined to be performed when an integral value calculated as the change state from the envelope exceeds a predetermined threshold value.