The object of the present invention is to provide a technology that enables long-term preservation while maintaining the function of an organ or tissue for transplantation. A further object is utilizing this technology to provide a technology for suppressing tissue disorder accompanying warm ischemia and reperfusion as well as restoring an organ from a cardiac arrest donor to a level compatible for transplantation. A long-term maintenance method of a mammalian organ or tissue for transplantation that employs perfusion by a perfusate etc. is provided, comprising each ofthe following steps of (a) connecting a perfusate instream cannula for streaming said perfusate into said "organ or tissue," (b) connecting a perfusate outstream cannula for streaming said perfusate out from said "organ or tissue," and (c) perfusing a perfusate comprising an oxygen carrier and a blood coagulation inhibitor into said organ or tissue.
