Disclosed is a liquid formulation which allows long-acting G-CSF conjugates, that have improved in vivo duration and stability, to be stable when stored for a long period of time. It comprises a stabilizer composition characterized by buffer and mannitol. Being free of human serum albumin and other potential factors harmful to the body, the liquid formulation is free of concerns about viral infections and guarantees excellent storage stability to long-acting G-CSF conjugates.
