In Kubiki district many high angle directional wells have been drilled to develop off-shore gas fields. In drilling a well with defflection angle of more than 45 degree, a severe balling-up around a bit and drillpipes occurs occasionally and it causes a low drilling speed. To solve this problem quantity of cuttings per unit length were measured throughout a drilling of a wall. As a result of analyzing these data, were obtained the conclusion that factors such as circulating rate of drilling mud, physical properties of drilling mud and etc. relate directly with the balling-up in directional drilling.