Powder neutron diffraction measurements were carried out for the ruthenium pyrochlore oxide Er2Ru2O7. The magnetic structure for this compound at 3.0 K has been solved using Rietveld analysis. The observed magnetic reflections suggest that the magnetic transitions are regarded as those to a long-range ordered state. It seems that the magnetic order of the Ru4+ and Er3+ magnetic moments occurs at 90 and 10K, respectively. (C) 2003 Elsevier Inc. All rights reserved.