An object is to respectively excite transmission coils with different voltages using a single power supply with low power consumption in an electromagnetic induction type encoder. A detection head of an encoder includes a voltage adjustment circuit and a plurality of excitation circuits. The excitation circuit includes a resonant circuit that includes a driving capacitor and a transmission coil connected in series and generates an alternate-current magnetic field inducing currents in scale coils disposed in a plurality of scale tracks on a scale by connecting both ends of the resonant circuit in a state in which the driving capacitor is charged. The voltage adjustment circuit includes a first transformer capacitor and controls a charging voltage of the driving capacitor in a single excitation circuit using the charged first transformer capacitor.