A new use of exosomes extracted from mesenchymal stem cells derived from a healthy individual co-cultured with melatonin or a culture solution thereof, for the treatment of chronic kidney disease is disclosed. A pharmaceutical composition containing the exosomes extracted from mesenchymal stem cells derived from a healthy individual co-cultured with melatonin or a culture solution thereof as an active ingredient and a method for preparing the pharmaceutical composition are disclosed. The exosomes promote the proliferation of mesenchymal stem cells derived from a chronic kidney disease patient or increase the survival rate of the patient.