Abstract: The invention provides a filler for ink jet recording paper which is composed of an amorphous silica containing 0.3-1.0% by weight of Al.sub.2 O.sub.3 and having a BET specific surface area of 250-400 m.sup.2 /g, a mean particle size of 3.6-10.0 .mu.m and a peak position of pore radius as measured by mercury injection method of 37.5-75 angstrom. A coat layer of ink jet recording paper formed of this filler excels not only in true circle property of dots and ink absorbing property when printed by ink jet recording system, but also in surface strength and writing quality. Furthermore, the coating liquid containing this filler has a low viscosity and hence exhibits good coating workability.