Of safety technologies of coal mines summarized as a handbook, described is the safety technology on thermal environmental control. Aggravation of the thermal environment at working faces affects health, safety and productivity. What controls capacity of heat dissipation from human body into the exterior is temperature, humidity and wind velocity, and besides, various thermal environment indices for increasing working efficiency are presented. As heat sources, geothermy, heat from machinery, air compression heat and others are cited. Measurements of rock mass temperature and air temperature/humidity and calculation methods of temperature/humidity of air flow are introduced. When the thermal environmental conditions become worse, increasing of air flow rate and mine cooling by refrigerator are usually conducted. However, the most reasonable measures should be taken in view of various points because they are closely related to cost, production and safety. The high temperature problem is apt to occur especially at working faces. Measures against hot water discharge are boring drain, grouting, etc. Cold water spray is also adopted to hot rock mass. Some examples of measures for thermal environmental control are explained. 6 refs., 56 figs., 16 tabs.