Interference light and the reflector 5 to the optical fiber sensor 2 FBG portion 3 formed with a plurality of, for forming a reference light, a light source 6 for switching and outputting stepwise light of a predetermined wavelength spacing, along with splitting the light a coupler 7 that generates a detection unit 8 for detecting the interference light, a calculating section 9A based on the detection result of the detection unit 8 calculates the amount of deformation of the FBG section 3, the medical device 1 having a.複数のFBG部3が形成された光ファイバセンサ2と、参照光を形成する反射器5と、所定間隔の波長の光を段階的に切り替えて出力する光源6と、光を分割するとともに干渉光を生成するカプラ7と、干渉光を検出する検出部8と、検出部8の検出結果に基づき、FBG部3の変形量を算出する算出部9Aと、を有する医療機器1。
