An electrocardiogram measuring apparatus includes: a population coefficient calculating unit which calculates: first population coefficients and second population coefficients a personal coefficient calculating unit which calculates: first personal coefficients and second personal coefficients and a lead deriving unit which: calculates first personal coefficients of a specific subject based on: a relationship between a magnitude of a ratio of the first population coefficients to the second population coefficients, and a magnitude of a ratio of the first personal coefficients to the second personal coefficients and second personal coefficients of the specific subject which are calculated based on A leads of the specific subject, the A leads being acquired by electrocardiogram measurement and synthesizes B leads of the specific subject by using the first personal coefficients of the specific subject.
