Disclosed is a sheet for use as a packaging material having a low percentage thermal shrinkage, outstanding flexibility and outstanding properties as a packaging material for solar cells. The sheet for use as a packaging material for solar cells according to the present invention is a resin sheet having air spaces obtained by the hot-melt bonding of a portion of a dispersed hot-bonding resin powder, wherein the apparent density of the sheet is no less than 20(%) and no more than 70(%) of the net density of the hot-bonding resin, such that the sheet is adequately flexible.