An electromagnetic flowmeter comprises a measuring pipe through which fluid to be measured flows, an electrode provided therein, an exciting unit, a signal line, a signal conversion unit that extracts a ∂A/∂t component that results from a change in the magnetic field from a resultant electromotive force of an electromotive force of the ∂A/∂t component; and an electromotive force of a v×B component that results from a flow speed of the fluid, wherein the resultant electromotive force is detected by the electrode and the signal line; and a flow rate output unit that eliminates, based on the extracted ∂A/∂t component, a variation factor as to a span that is a coefficient applied to a magnitude V of a flow speed of the v×B component in the resultant electromotive force so as to calculate a flow rate of the fluid.