Magnetostrictive type sensor temperature detecting circuit, magnetostrictive type sensor, and temperature detecting method for magnetostrictive type sensor

A magnetostrictive-type sensor temperature-detecting circuit configured to be used in a magnetostrictive-type sensor including an applied stress-detecting coil, and a driving section to output an alternating voltage, excite the coil with a resulting alternating electric current, and switch flow directions of the electric current flowing in the coil in response to switching voltage polarities of the output alternating voltage, to detect a temperature of the coil in the sensor. This temperature-detecting circuit includes an alternating electric current direction switching time-detecting section to detect an amount of time from when the voltage polarities of the output alternating voltage are switched until when the flow directions of the electric current flowing in the coil are switched, and a temperature-computing section to compute the temperature of the coil on the basis of the amount of time detected by the alternating electric current direction switching time-detecting section.