The purpose of this study is to propose a palm-sized cryoprobe system with a built-in thermocouple for highly accurate temperature measurements at the probe-tip wall. The conventional and general configuration of cryoprobe systems uses triple coaxial tubes. Moreover, in order to measure the temperature shift at the probe tip, a wired thermocouple is attached externally using adhesive. However, because the adhesive creates thermal resistance between the wired thermocouple and the external surface of the probe tip, the temperature measurement accuracy deteriorates. To cope with this problem, in this paper, we propose a cryoprobe system with a built-in thermocouple.