Preservation method of polyelectrolyte type fuel cell stack and preservation treatment object of polyelectrolyte type fuel cell stack

A storing method for a PEFC stack to suppress the deterioration of the performance of a PEFC stack in a period between an uninstalled state and an installed state in an installation place for use and a storably treated body of the PEFC stack capable of sufficiently preventing the performance of the PEFC stack from being deteriorated in the period between the uninstalled state and the installed state in the installation place for use. The storing method for the PEFC stack (200) is a method for storing the PEFC stack (200) comprising oxidizer flow passages (30) having inlets and outlets and passed through cathodes and reducer flow passages (40) having inlets and outlets and passed through anodes. For storage, the insides of the oxidizer flow passages (30) and the reducer flow passages (40) of the PEFC stack (200) in the uninstalled state are brought into a state where an oxygen concentration is lower than that of the atmosphere.