A magnetic permeability detector comprising: an LC oscillator circuit including a coil and a capacitor (103,104); and a resistor connected in series with the coil, wherein: the resistor adds a predetermined resistance value to a circuit resistance value of the LC oscillator circuit, an oscillation frequency of the LC oscillator circuit being dependent on the circuit resistance value and the predetermined resistance value, wherein the resistor functions as a resistance adjuster that does not affect inductance of the coil even when the predetermined resistance value of the resistor is changed; the coil generates a magnetic flux in a predetermined direction by a current flowing through the coil upon application of a power supply voltage to the magnetic permeability detector, the magnetic permeability detector further comprises an output terminal to output a signal having a frequency corresponding to a magnetic permeability in a range of action of the magnetic flux; and the predetermined resistance value of the resistor makes a temperature characteristic of the frequency of the signal output from the output terminal closer to a temperature characteristic of a reference clock based on which the signal output from the output terminal is counted. an LC oscillator circuit including a coil and a capacitor (103,104); and a resistor connected in series with the coil, wherein: the resistor adds a predetermined resistance value to a circuit resistance value of the LC oscillator circuit, an oscillation frequency of the LC oscillator circuit being dependent on the circuit resistance value and the predetermined resistance value, wherein the resistor functions as a resistance adjuster that does not affect inductance of the coil even when the predetermined resistance value of the resistor is changed; the coil generates a magnetic flux in a predetermined direction by a current flowing through the coil upon application of a power supply voltage to the magnetic permeability detector, the magnetic permeability detector further comprises an output terminal to output a signal having a frequency corresponding to a magnetic permeability in a range of action of the magnetic flux; and the predetermined resistance value of the resistor makes a temperature characteristic of the frequency of the signal output from the output terminal closer to a temperature characteristic of a reference clock based on which the signal output from the output terminal is counted. the resistor adds a predetermined resistance value to a circuit resistance value of the LC oscillator circuit, an oscillation frequency of the LC oscillator circuit being dependent on the circuit resistance value and the predetermined resistance value, wherein the resistor functions as a resistance adjuster that does not affect inductance of the coil even when the predetermined resistance value of the resistor is changed; the coil generates a magnetic flux in a predetermined direction by a current flowing through the coil upon application of a power supply voltage to the magnetic permeability detector, the magnetic permeability detector further comprises an output terminal to output a signal having a frequency corresponding to a magnetic permeability in a range of action of the magnetic flux; and the predetermined resistance value of the resistor makes a temperature characteristic of the frequency of the signal output from the output terminal closer to a temperature characteristic of a reference clock based on which the signal output from the output terminal is counted.