The present invention relates to a process for preparing regenerated collagen fiber which comprises treating regenerated collagen fiber with a monofunctional epoxy compound and a metal aluminum salt, in which treatment with the monofunctional epoxy compound initiated by adding sodium hydroxide to become 0.001 to 0.8 N based on the treatment solution and inorganic salt in an amount so that water absorption of the obtained regenerated collagen fiber becomes at most 100%, depending on amount of sodium hydroxide added. Also, the present invention relates to a process for setting regenerated collagen fiber obtained by the above process which comprises thermally setting the fiber by means of wet heat treatment at 50.degree. to 160.degree. C. and drying treatment at 20.degree. to 220.degree. C.