CaCu3Ti4O12 thin films were prepared on Pt/Ti/SiO2/Si substrate by a sol-gel method. A ferroelectric hysteresis loop was obtained at room temperature for amorphous CaCu3Ti4O12 thin film. The ferroelectric characteristic of amorphous CaCu3Ti4O12 thin film was corroborated by the observation of piezoresponse force microscopy. The result indicates that there exists correlated intrinsic electric dipole moment in amorphous CaCu3Ti4O12 thin film, and the origin of ferroelectricity in amorphous CaCu3Ti4O12 thin film is also discussed. (C) 2011 Elsevier B.V. All rights reserved.