This paper describes a flexible cryoprobe utilizing the Peltier effect. The conventional cryoprobes have problems such as low flexibility and difficulty in precise temperature control. In this study, the cryoprobe composed of a flexible tube was developed to treat the inner part of the human body. The thermoelectric elements are attached on the top of the cryoprobe, so the Peltier effect makes it possible to control the heat-transfer of the cooling tip actively and to perform both cooling and heating only by reversing the electric current. The performance of the cryoprobe was evaluated through experiments of agar gel cooling and the temperature distribution was estimated by numerical simulation. In addition, an animal experiment using a guinea pig was conducted for practical application. In the experiment of an agar gel cooling, the agar gel surface was frozen within 10 seconds, which is in good agreement with numerical simulations. Repetition of cooling and heating are also performed experimentally. In the animal experiments, the temperature of the skin surface was monitored and its histological change was examined. Although the continuous cooling for 500 sec after freezing the skin surface could induce only the focal necrosis of the epidermis, the cyclic treatment of cooling and heating induced the necrosis of the whole epidermal layer and a part of eccrine glands. From experimental and numerical results, the cryoprobe could induce the necrosis of the skin.