According to an embodiment, an electrocardiograph includes first and second electrode pairs, first and second detectors, and an electrocardiogram detector. A difference between a first distance between two electrodes of the first electrode pair on a first line and a second distance between two electrodes of the second electrode pair on a second line is not more than a first threshold. An angle formed by the first and second lines is not less than a second threshold. The first detector is configured to detect a first differential electric potential of the first electrode pair. The second electric potential detector is configured to detect a second differential electric potential of the second electrode pair. The electrocardiogram detector is configured to detect an electrocardiogram by performing a subtraction process on the first and second differential electric potentials.
