The purpose of this study is to identify the effect of particle shape on stress dip underneath granular piles based on the results of laboratory-scale experiments using a high sensitivity stress sensor mat system. Two different granular materials with contrasting particle shapes but in similar size ranges were evaluated. Wedge-shaped and conical piles of granular materials were formed by pouring using a local source method. Stress dip at the center was measured in all piles but with different developing situations. We suggest the use of the ratio of the maximum stress over the dipped stress value at the center as a quantitative index to assess the stress dipping effect We observed that a higher elongation of the particle shape would yield a more profound stress dip under the pile. When piles of the same material but in various pile shapes are compared, stress dip is found to be more profound, and the influence of the particle shape is more obvious in a 3-d axisymmetic conical pile than in a 2-d plane-strain wedge-shaped pile. The reason is that a larger elongation of the particle shape be helpful for more steady arches with strong force chains formed to support more weight of the middle part of the pile, especially in a 3-d axisymmetic configuration. (C) 2017 Published by Elsevier B.V.