In the present paper, the distribution of stress intensity factor along a small three-dimensional crack front locating at a vertex in an elastic block is investigated precisely. A tensile load is applied to the block with a small crack. Boundary element method is used for analyzing the stress distribution and eigenanalysis is conducted for determining the order of stress singularity at the intersection point of crack front and the free surface. The stress distribution near the intersection point is formulated using the distance from the intersection point and the angular functions derived from the eigenanalysis. The relationship between the stress intensity factor and the distance from the intersection point is confirmed by the comparison of the result obtained from the stress singularity analysis.
