To obtain a temperature controller for a floor heating system in which the temperature of a plurality of floor mats can be set individually and the temperature is distributed uniformly in the same mat even when the temperature is set at a low level.

The floor heating system for supplying hot water from a single heat source 1 to a plurality of floor mats 2a, 2b and 2c is provided with paths 3a, 3b and 3c for circulating hot water from the hot water outlet of each floor mat 2a, 2b, 2c to the hot water inlet thereof and high temperature water for temperature regulation is injected from mixing valve 4a, 4b and 4c provided on the hot water inlet side of the circulation paths 3a, 3b and 3c. The circulation paths 3a, 3b and 3c are combined into a circulation path 5 and coupled with a circulation pump 6. A return pipe 7 is branched from the downstream side of the circulation pump 6 to the heat source 1 and a supply pipe 8 therefrom is branched into a plurality of pipes being coupled to the high temperature side of the mixing valve 4a, 4b and 4c.