Cellulosic fiber or cellulosic fiber product treatment method

The invention provides a cellulosic fiber or a cellulosic fiber product treatment method that imparts a cellulosic fiber or cellulosic fiber product a capability to attain substantially the same cleaning effect as when a cleanser is used, even when laundered without the use of a cleanser, and accomplishes high flexibility and durability to washing, and a cellulosic fiber or cellulosic fiber product. The cellulosic fiber or cellulosic fiber product treatment method has a process that hydrophilically treats the cellulosic fiber or the cellulosic fiber product, and a process that cross-links hydrophilically treated cellulosic fiber or cellulosic fiber product using an ester finishing agent and carbodiimide crosslinking agent. The cellulosic fiber or cellulosic fiber product contains an ester compound generated by esterification of the ester finishing agent and modified polyethylene oxide or an acid modified polyethylene, and aliphatic alcohol or aliphatic amine ethylene oxide and/or propylene oxide adducts.