To provide a stable concentrated perglutaric acid composition storable at a low temperature and usable as sterilizing agents, bleaching agents, washing agents, epoxidizing agents, etc., and to provide a sterilization method using the perglutaric acid composition.

The invention provides an equilibrated perglutaric acid composition containing 10-35 wt.% perglutaric acid, 1-30 wt.% glutaric acid and 8-35 wt.% hydrogen peroxide, wherein the ratio of the total molar concentration of the hydrogen peroxide and the peroxycarboxyl group to the molar concentration of water in the composition is adjusted to 0.01-0.35, and a sterilizing and disinfecting method comprising the contact of the sterilizing object with the equilibrated perglutaric acid composition at 10-60C for 1-60 min with or without diluting the composition.