The invention provides a method for selecting and eliminating endotoxin selectively from a solution where a highly acidic substance such as heparin co-exists, and an adsorbent used therefore. The invention also provides a method for providing the endotoxin adsorbent, which includes partially modifying amino groups contained within an amino group-containing molecule used as a ligand of the endotoxin adsorbent, with a molecule that is capable of reacting with an amino group.
