A silica-based particle dispersion including a silica-based particle group and a high polishing rate and high surface precision is achieved to a silica-based substrate or a NiP-plated substrate to be polished or the like. A silica-based particle dispersion containing a group including irregularly-shaped and non-irregularly-shaped silica-based particles, wherein the irregularly-shaped silica-based particles each have a plurality of small holes thereinside and a covering silica layer which covers the core, and the silica-based particle group satisfies [1]-[3]. [1] Having an average particle size (D1) of 100-600 nm, and a particle size (D2) of 30-300 nm in terms of specific surface area. [2] An irregular-shape degree D (D=D1/D3) represented by the average particle size (D1) and a projected area-equivalent particle size (D3) being in the range of 1.1-5.0. [3] When waveform separation is performed on a volume-reference particle size distribution, a multi-peak distribution in which three or more peaks are detected.