The optical Faraday effect hysteresigraph is an instrument for measuring the static thermomagneto‐optic properties of thin transparent magnetic film samples. Via an oscilloscope, it displays 60 Hz magnetic hysteresis loops of the samples over a temperature range of 20°C±40°, with peak magnetic fields of 2600 Oe. Its use of thermoelectric elements results in a compact package, highly effective for rapid change and accurate control of sample temperature.