The objective of the present invention is to provide a method for efficiently supporting a thiol group-including compound on an insoluble base material. The method for supporting a thiol group-including compound on an insoluble base material according to the present invention is characterized in comprising Step A: treating the thiol group-including compound with a thiol group-including organic reducing agent and an inorganic reducing agent, and Step B: contacting a reaction liquid of said Step A with the insoluble base material.