To provide a compost manufacture support method and system capable of stably manufactuing good-quality compost without relying on a manufacturer's experience and intuition, and to provide a program.

In a primary fermentation period, the measured values of a temperature sensor 21 and a moisture content sensor 22 are monitored and when the measured values of the temperature and moisture content of the compost deviate from the permissible range in the primary fermentation period previously determined respectively, the corresponding process previously determined by each case is performed. In a secondary fermentation period, the measured values of the temperature sensor 21, the moisture content sensor 22, and a pH sensor 23 are monitored and when the measured values of the temperature, moisture content and pH of the compost deviate from the permissible range in the secondary fermentation period previously determined respectively, the corresponding process previously determined by each case is performed. In a ripening period, the measured values of the temperature sensor 21, the moisture content sensor 22, the pH sensor 23, and an electric conductivity sensor 24 are monitored and when the measured values of the temperature, moisture content, pH, and electric conductivity of the compost deviate from the permissible range in the ripening period previously determined respectively, the corresponding process previously determined by each case is performed.