Neutron diffraction measurements have been carried out for Li-6/Li-7 isotopically substituted aqueous 1.0 mol % (0.5 mol/kg) LiCl and 1.1 mol % (0.56 mol/kg) LiClO4 solutions in D2O to obtain structural insight concerning hydration structure of Li+ in more dilute electrolyte solutions. The first-order difference function, Delta(Li)(Q), was analyzed by means of the least squares fitting procedure to obtain short-range structural parameters around the Li+. It was revealed that the nearest neighbor Li+center dot center dot center dot O(D2O) distance, r(LiO), and the coordination number, n(LiO), for the aqueous 1.0 mol % LiCl solution are 2.01 +/- 0.02 angstrom and 5.9 +/- 0.1, respectively. The values, r(LiO) = 1.97 +/- 0.02 angstrom and n(LiO) = 6.1 +/- 0.1, are obtained for aqueous 1.1 mol % LiClO4 solution. These results indicate that the hydration number of Li+ in a dilute solution is close to 6, which is much larger than 4, which has long been believed. A possible explanation is that the hydration number of Li+ varies with the solute concentration.