Constant temperature liquid bath

The present invention provides a constant temperature liquid bath using a thermo-module in which even if an article whose temperature is to be controlled exists in the bath, heat is efficiently exchanged between a heat source and liquid, and the temperature of the liquid is efficiently adjusted to a constant value, and the temperature can easily and swiftly be adjusted. A constant temperature liquid bath which adjusts temperature of liquid in the bath by a heat supply apparatus having a thermo-module that adjusts temperature by Peltier effect comprises an outer bath for storing the liquid, an inner bath disposed in the outer bath through a gap, and provided at its sidewall with holes which the liquid flows into the inner bath from the outer bath and provided with at a central portion of its bottom with an opening, and an agitator which introduces upward the liquid which flows from the opening of the bottom of the inner bath between sidewalls of the inner and outer baths by means of a rotor blade disposed on a central portion of a bottom between the outer bath and the inner bath, the thermo-module is mounted on an outer surface of the sidewall of the outer bath, the temperature of the liquid flowing between the inner and outer baths is controlled to a set value.