A derived electrocardiogram generating system comprising: a personal coefficient database configured to store personal coefficients specific to a subject, the personal coefficients being acquired from the subject; a population coefficient database configured to store population coefficients which are average values of conversion coefficients acquired from an unspecified large number of persons belonging to a statistically significant population; and an electrocardiograph control portion: configured to generate a derived electrocardiogram of the subject using the personal coefficients when the personal coefficients are present in the personal coefficient database; and configured to generate a derived electrocardiogram of the subject using the population coefficients when the personal coefficients are absent in the personal coefficient database, further comprising: an electrocardiograph (110; 120; 130; 210; 220; 230) configured to generate the derived electrocardiogram of the subject; and an electrocardiogram management system (140; 240) configured to manage information about the derived electrocardiogram held by the electrocardiograph, characterized in that the personal coefficient database is disposed in each of the electrocardiograph and the electrocardiogram management system, and the population coefficient database and the electrocardiograph control portion are disposed in the electrocardiograph. a personal coefficient database configured to store personal coefficients specific to a subject, the personal coefficients being acquired from the subject; a population coefficient database configured to store population coefficients which are average values of conversion coefficients acquired from an unspecified large number of persons belonging to a statistically significant population; and an electrocardiograph control portion: configured to generate a derived electrocardiogram of the subject using the personal coefficients when the personal coefficients are present in the personal coefficient database; and configured to generate a derived electrocardiogram of the subject using the population coefficients when the personal coefficients are absent in the personal coefficient database, configured to generate a derived electrocardiogram of the subject using the personal coefficients when the personal coefficients are present in the personal coefficient database; and configured to generate a derived electrocardiogram of the subject using the population coefficients when the personal coefficients are absent in the personal coefficient database, further comprising: an electrocardiograph (110; 120; 130; 210; 220; 230) configured to generate the derived electrocardiogram of the subject; and an electrocardiogram management system (140; 240) configured to manage information about the derived electrocardiogram held by the electrocardiograph, an electrocardiograph (110; 120; 130; 210; 220; 230) configured to generate the derived electrocardiogram of the subject; and an electrocardiogram management system (140; 240) configured to manage information about the derived electrocardiogram held by the electrocardiograph, the personal coefficient database is disposed in each of the electrocardiograph and the electrocardiogram management system, and the population coefficient database and the electrocardiograph control portion are disposed in the electrocardiograph.