An inside air control system provided for a container housing breathing plants, the system comprising: adsorption columns (34, 35), each of which houses an adsorbent that is configured to adsorb a nitrogen component in air; a first pump mechanism which is configured to supply outside air to the adsorption columns (34, 35) to pressurize the adsorption columns (34, 35), thereby allowing each of the adsorption columns (34, 35) to perform an adsorption operation of adsorbing the nitrogen component in the air onto the adsorbent; and a second pump mechanism which is configured to suck the air from the adsorption columns (34, 35) to depressurize the adsorption columns (34, 35), thereby allowing each of the adsorption columns (34, 35) to perform a desorption operation of desorbing the nitrogen component adsorbed onto the adsorbent in the air, and an oxygen sensor for measuring an oxygen concentration of air in the container, wherein the inside air control system is configured to allow the adsorption columns (34, 35) to alternately perform the adsorption operation and the desorption operation so that nitrogen-enriched air having a higher nitrogen concentration and a lower oxygen concentration than the air is produced and supplied into the container, characterized in that an oxygen concentration of said nitrogen-enriched air is high just after a start of the desorption operation, and gradually decreases with time, wherein the inside air control system is configured to perform a whole supply operation of supplying the whole nitrogen-enriched air produced during a period from the start to end of the desorption operation into the container, and a partial supply operation of discharging to the outside of the container the nitrogen-enriched air produced for a predetermined time since the desorption operation was started, and then supplying into the container the nitrogen-enriched air produced until the end of the desorption operation since the predetermined time passed, wherein the inside air control system is further configured to perform a first control and/or a second control, wherein, in the first control, the whole supply operation is performed until an oxygen concentration of the air in the container reaches a predetermined concentration or lower, and the partial supply operation is performed when the oxygen concentration of the air in the container has reached the predetermined concentration or lower, in the second control, the partial supply operation is performed until an oxygen concentration of the air in the container reaches the predetermined concentration or lower, and the partial supply operation is performed even when the oxygen concentration of the air in the container has reached the predetermined concentration or lower. adsorption columns (34, 35), each of which houses an adsorbent that is configured to adsorb a nitrogen component in air; a first pump mechanism which is configured to supply outside air to the adsorption columns (34, 35) to pressurize the adsorption columns (34, 35), thereby allowing each of the adsorption columns (34, 35) to perform an adsorption operation of adsorbing the nitrogen component in the air onto the adsorbent; and a second pump mechanism which is configured to suck the air from the adsorption columns (34, 35) to depressurize the adsorption columns (34, 35), thereby allowing each of the adsorption columns (34, 35) to perform a desorption operation of desorbing the nitrogen component adsorbed onto the adsorbent in the air, and an oxygen sensor for measuring an oxygen concentration of air in the container, wherein the inside air control system is configured to allow the adsorption columns (34, 35) to alternately perform the adsorption operation and the desorption operation so that nitrogen-enriched air having a higher nitrogen concentration and a lower oxygen concentration than the air is produced and supplied into the container, characterized in that an oxygen concentration of said nitrogen-enriched air is high just after a start of the desorption operation, and gradually decreases with time, wherein the inside air control system is configured to perform a whole supply operation of supplying the whole nitrogen-enriched air produced during a period from the start to end of the desorption operation into the container, and a partial supply operation of discharging to the outside of the container the nitrogen-enriched air produced for a predetermined time since the desorption operation was started, and then supplying into the container the nitrogen-enriched air produced until the end of the desorption operation since the predetermined time passed, wherein the inside air control system is further configured to perform a first control and/or a second control, wherein, in the first control, the whole supply operation is performed until an oxygen concentration of the air in the container reaches a predetermined concentration or lower, and the partial supply operation is performed when the oxygen concentration of the air in the container has reached the predetermined concentration or lower, in the second control, the partial supply operation is performed until an oxygen concentration of the air in the container reaches the predetermined concentration or lower, and the partial supply operation is performed even when the oxygen concentration of the air in the container has reached the predetermined concentration or lower.