Recently, it becomes a problem that the deicing/anti-freezing agents (Agents) spread over a road have an influence on the environment. And it is demanded to reduce the amount of the Agents used in the winter road maintenance. But as the winter road-surface conditions are changeable, it is very difficult to spread the suitable amount the Agents for the road condition timely. In order to solve this problem, our company which is the manufacture of Agents, has tried to research and develop the winter road-surface monitoring system from 1989. Features of our system are as follows: (1) Road condition data such as an air temperature, a road-surface temperature, snowfall and pictures of the road can be displayed on the same screen of a personal computer on real time; (2) With the buried sensor below the road, we can get the changing concentration of the Agents (i.e. road-surface freezing temperature); (3) By the picture on the display, we can know the changing condition of the road every moment; and (4) We can improve the reliability of weather forecasts to link our System to the other weather forecast system. Our System installed in Morioka-city from 1998 to 2000 demonstrated the following effects: (1) From various data of our system, the spreading amount of the Agents and the spreading time could be optimized; as the result, the amount of the Agents spread could be reduced; (2) By installing the winter road-surface monitoring system at the city hall and the companies consigned spreading and sharing information of the road conditions each other, the good management of winter road could be attained; (3) As a result of using our System, the expense of spreading the Agents could be cut down about 20 per cent.