To carry out an effective insect repellent finishing without imparting an olfactory unpleasant feeling to humans by applying a neem-oil emulsion to a material for Tatami (a Japanese thick woven straw mat covered with woven rush grass) such as warps for a Tatami facing, the Tatami facing and a Tatami mat.

Warp yarns for a Tatami facing composed of hemp or a cotton raw yarn are passed through a paste liquid bath obtained by mixing 15-20% emulsion prepared by diluting a neem-oil stock solution 1:(30-50) with 10-15% synthetic paste such as polyvinyl alcohol and 65-75% water, squeezed, then predried, brushed in a damp-dried state, subjected to fuzz pressing and glazing, subsequently dried to 10-14% moisture content and wound onto a bobbin to afford insect repellent warp yarns. The neem-oil stock solution is diluted with a polyethylene glycol-based nonionic surfactant 1:(30-100) and the resultant emulsion is then sprayed on a Tatami facing or Tatami mat in 15 cc/m2 coating quantity to carry out the insect repellent finishing.