To enable digital display of a temperature by a method wherein a current flowing in an oscillating member and a coil into which the part is inserted is measured, and a temperature change is detected from a current change corresponding to an oscillating displacement of the oscillating member.

In a bimetal 12, an inner end part located on a center side of a spiral is fixed to a rotary axis 11 provided an electric insulating substrate 10, and the rotary axis 11 is rotated by expansion and contraction acts corresponding to a temperature change. An oscillating member 13 has a linear part 13a extending to both directions centering the attached rotary axis 11 and a pair of curve part 13b extending in an arc-shaped manner on both end sides and to both directions of the linear part 13a and oscillates and displaces by rotation acts of the rotary axis 11. Coils 14 to 17 are fixed and disposed in each displacement region to insert a part of both the curve parts 13b and are connected in 4-side bridge form, and the insertion amounts on both top end sides of each curve part 13b are respectively fluctuated in response to oscillating displacement of the member 13. A voltage is applied to these coils and a current flowing therein is measured by an ammeter 19 and a temperature change is detected from a current change corresponding to the oscillating displacement of the member 13.