Abstract: An apparatus for controlling the temperature of a fluid by use of a thermoelectric device comprises at least one temperature control unit, which is composed of a first heat-transfer member having at least one channel, through which the fluid flows, a pair of thermo-modules each incorporating the thermoelectric device, which are placed on opposite surfaces of the first heat-transfer member, and a pair of second heat-transfer members, each of which has a flange on its periphery and is placed on the thermo-module. The temperature control unit is stably held between a pair of holding frames each having an aperture such that each of the holding frames is pressed against the flange of the second heat-transfer member through a sealing material having elasticity, and a part of the second heat-transfer member is exposed through the aperture. This apparatus is capable of cooling the fluid without chlorofluorocarbons (CFCs) used as a coolant for conventional refrigerators.