PROBLEM TO BE SOLVED: To improve degradation ability of VOC (Volatile Organic Compounds) and shorten a period of purification processing of contaminated soil and groundwater by specifying an anaerobic microorganism activator and a temperature appropriate range and increasing ground temperature to temperature appropriate range in purifying the soil and the groundwater by utilizing anaerobic biostimulation.SOLUTION: There is provided a soil and groundwater purifying method in which contaminated soil and groundwater are purified by utilizing anaerobic biostimulation. An anaerobic microorganism activator is added into the ground, and the ground is heated to less than 35°C. Adding the anaerobic microorganism activator into the ground and directly heating the ground can make the ground optimum condition for the activity of microorganism. By directly heating the ground and heating the ground to the temperature of less than 35°C, activation of microorganism is promoted to improve the degradation ability of VOC and
