A terahertz (THz) detector based on thermoelectric thin films was simulated using the finite elements method. The thermoelectric circuit consisted of S b and B i 88 S b 12 150-nm films on the mica substrate. S b , B i 88 S b 12 , and mica-substrate properties have been measured experimentally in the THz frequency range. The model of electromagnetic heating was used in order to estimate possible heating of S b - B i 88 S b 12 contact. THz radiation power varied from 1 μ W to 50 mW, and frequency varied in the range from 0.3 to 0.5 THz. The calculations showed a temperature difference of up to 1 K, voltage up to 0.1 mV, and responsivity of several mVW − 1 . The results show that thin S b and B i − S b thermoelectric films can be used for THz radiation detection at room temperatures.