An electromagnetic flowmeter includes a board having a preamplifier circuit and a shield case mounted thereon. The preamplifier circuit amplifies an electromotive force generated between first and second electrodes disposed to be perpendicular to a magnetic field generated by an exciting coil on a measurement pipe. The preamplifier circuit includes first and second operational amplifiers, a first wiring connecting the first electrode and a non-inverting input terminal of the first operational amplifier, a second wiring connecting the second electrode and a non-inverting input terminal of the second operational amplifier, a first resistor connecting an output terminal and an inverting input terminal of the first operational amplifier, a second resistor connecting an output terminal and an inverting input terminal of the second operational amplifier, and a third resistor connecting the inverting terminals of the first and second operational amplifiers.