To sufficiently purify contaminated soil by making fuel consumption of a burner as little as possible, and effectively removing oil contents in the contaminated soil.

This treatment device 1 of contaminated soil comprises a rotary kiln 2 drying and heating oil contaminated soil (treatment material) M inserted into the inside by a quantitative feeder (material supply device) 3 to evaporate oil contents; a deodorant furnace (combustion furnace) 5 introducing exhaust gas including evaporated oil contents discharged from the rotary kiln 2 via a refractory-lined duct 4 and combusting the oil contents in the exhaust gas; an exhaust gas cooling device 7 introducing and cooling the exhaust gas exhausted from the deodorant furnace 5 via a duct 6; a bag filter (dust collector) 9 collecting the dust in exhaust gas introduced from the exhaust gas cooling device 7 via a duct 8; and a chimney 12 releasing the exhaust gas from the bag filter 9 to the atmosphere.