An in-vehicle electrocardiograph device includes: a direct electrode that is used to detect an electric potential of a body of a vehicle occupant in a state in which the direct electrode contacts a skin of the occupant a capacitive-coupled electrode that is used to detect the electric potential of the body of the occupant in a state in which the capacitive-coupled electrode does not contact the skin of the occupant and an electrocardiographic waveform determination unit that determines an electrocardiographic waveform of the occupant based ON an electric potential at the direct electrode and an electric potential at the capacitive-coupled electrode.
