Neutron diffraction measurements were performed on powder Cu2O with different samples that are pressure released after a pressing force of 295 K with iMATERIA (IBARAKI Materials Designed Diffractometer) installed at MLF in J-PARC. Peak widths of Bragg lines increased depending on the pressing force. To clarify the relation between the crystallite size and the microstrain effect, Rietveld refinement analysis on a TOF neutron diffraction pattern of Cu2O was performed by assuming a cubic cuprite type structure (space group Pn-3m). Strain and crystallite size effects were estimated from Lorentzian terms in the Pseudo-Voigt profile function with a pair of Back-to-Back exponential types based on the Stephenes model. It is considered that the increasing peak width according to the dependence of pressing force is mainly derived from strain effects. And this result is consistent with the previous studies of Ag2O where the Williamson-Hall plot method by X-ray diffraction was applied. (C) 2013 Published by Elsevier B.V.