The present invention relates to a pharmaceutical composition for the prevention and treatment of non-alcoholic fatty liver disease (NAFLD), including a conjugate prepared by covalently linking an insulinotropic peptide, a non-peptidyl polymer and an immunoglobulin Fc region. The composition of the present invention maintains the in-vivo activity of the peptide at a relatively high level, and remarkably increases the blood half-life, thereby preventing triglyceride accumulation which is a typical feature of non-alcoholic fatty liver disease. Ultimately, it can be desirably employed for the prevention and treatment of non-alcoholic fatty liver disease.