To provide a resin liquid impregnating method capable of uniformly and continuously supplying a resin liquid in the ground while performing the method without practically requiring manpower.

A filtering material 3 selected from Japanese paper, gauze or cotton is laid on the surface of the ground 1 to be preserved, and nonwoven fabric 5 is also laid of the filtering material 3. A resin liquid 9 such as an acrylic resin and a silane resin stored in a resin liquid tank 7 is dripped on the surface of the nonwoven fabric 19 from a dripping port 19 by passing through plural tubes 17, 17 from a main tube 13. The resin liquid 9 is impregnated into the ground 1 by expanding as a plane to the surface of the ground 1 from the filtering material 3 after dripping on the surface of the nonwoven fabric 5. Since meshes of the filtering material 3 are fairly fine, the resin liquid 9 hardly permeates, and is held as a liquid film 9A between the filtering material 3 and the nonwoven fabric 5 to expand in a plane shape along the meshes of the filtering material 3. The permeated resin liquid 9 is also held on the under surface of the filtering material 3 as a liquid film 9B, and the surface of the ground is always covered with the resin liquid 9.