To achieve a rational and effective grouting technique which takes into consideration a geological state.

A quality management support method of a grouting technique includes the steps of: confirming a predominant fracture system from fractures distributed in a rock mass before drilling of a plurality of injection holes; calculating the number of fractures crossing a unit length of each hole three-dimensionally drilled in an optional direction to the fracture system; calculating a drilling direction most probably crossing the fractures from the result of the above calculation; performing a water permeability test of each injection hole before grout injection, for each time of drilling the injection hole while changing the interval between the holes after first time of drilling of the plurality of injection holes at predetermined intervals; performing a geostatistical analysis by using the above result to estimate water permeability between the injection holes; and thus confirming an improved state of the rock mass.