PROBLEM TO BE SOLVED: To provide a medical instrument, for example, facilitating disinfection and sterilization work, being sanitary, and capable of suppressing excessive increase in a surface temperature.SOLUTION: A medical instrument (10) includes: a Peltier element (100) having a first surface (1001) and a second surface (1002)； control means (830) performing first electrification control for the Peltier element to make the first surface an endothermic surface and make the second surface a heat-radiating surface； a latent heat storage agent (16) disposed on the second surface, while retaining a thermal contact state therewith； housings (11F and 11R) that store the Peltier element and the latent heat storage agent, with a heat-conductive member exposed therefrom, the heat conductive member covering the first surface or at least a part of the first surface.【課題】例えば、消毒滅菌作業が容易であり、衛生的であり、表面温度の過剰な上昇を抑制し得る医療機器を提供する。【解決手段】医療機器（１０）は、第１の面（１００１）と第２の面（１００２）とを有するペルチェ素子（１００）と、前記ペルチェ素子に対し、前記第１の面が吸熱面、且つ、前記第２の面が放熱面となる第１の通電制御を実行する制御手段（８３０）と、前記第２の面に熱的接触状態を保って配置された潜熱蓄熱剤（１６）と、前記第１の面又は前記第１の面の少なくとも一部を覆う熱伝導性部材が露出した状態で前記ペルチェ素子及び前記潜熱蓄熱剤を収納する筐体（１１Ｆ、１１Ｒ）とを備える。【選択図】図２
