<；P>；PROBLEM TO BE SOLVED: To provide an air-conditioning method in a multistage plant-cultivation device provided with an artificial lighting device and a plurality of air conditioners in a closed structure, comprising independently and sensitively controlling the operation of each of the air conditioners to suppress moisture increase in the inner space of the closed structure through a lighting period and a dark period and generation of mold inside the air conditioners. <；P>；SOLUTION: The air-conditioning method in a multistage plant-cultivation device comprises performing warming operation by one of the air conditioners when the artificial lighting device is put off and cooling load in the inner part of the closed construction is decreased during the dark period of plant growth, and performing cooling operation by remaining air conditioners to maintain moisture-elimination effect and suppressing the moisture increase in the inner space of the closed construction. It is desirable to sequentially exchange one of the air conditioners performing warming operation in a plurality of air conditioners. <；P>；COPYRIGHT: (C)2008,JPO&INPIT
