Polycrystalline YMnO3 (YMO) thin films were deposited on (111) Pt/Ta/glass substrates via pulsed laser deposition (PLD). The low PLD deposition rate made it possible to reduce the leakage currents of the YMO thin film due to the resulting high level of crystallinity. The YMO thin film exhibited a strong ferroelectric response, including a remnant polarization of 4.2 mu C/cm(2). The piezoresponse force microscopy study revealed that the YMO thin films had a mosaic domain structure and a ferroelectric domain wall energy lower than that of PbTiO3 thin films. It is suggested that the fast switching speed of YMO capacitors, which is below 85 ns, originates from this low domain wall energy. (C) 2017 Elsevier B.V. All rights reserved.