PROBLEM TO BE SOLVED: To provide an air circulating system in a greenhouse capable of eliminating the stagnation of air felt uncomfortable by persons at work in the greenhouse, improving the environment in the greenhouse and promoting the growth of plants. SOLUTION: This air circulating system 1 in a greenhouse 2 is equipped with the required number of fans 3 for circulating air in the greenhouse 2 for growing plants and a control panel for controlling the fans 3.