In an inside air control system, a first pump supplies treatment target air to an adsorption vessel, and a second pump sucks gas from the adsorption vessel. In an adjustment operation of adjusting the composition of air in a storage, the inside air control system alternately performs a first action and a second action. When a stop condition for stopping the adjustment operation is satisfied, a controller performs stop control. In the stop control, the controller controls the second pump to suck the gas from the adsorption vessel to which the first pump supplies the treatment target air when the stop condition is satisfied, and controls the second pump to stop after the second pump has operated for a first time T1.