The thiol-containing composition for an optical material of the present invention includes a compound (A) represented by General Formula (a), and a compound (B) composed of at least one selected from a compound (b2-1) represented by General Formula (b2-1), a compound (b3-1) represented by General Formula (b3-1), a compound (b3-2) represented by General Formula (b3-2), and a compound (b4-2) represented by General Formula (b4-2), in which, in high-performance liquid chromatography measurement, the total peak area ratio of the compound included in the compound (B) is 0.1% to 60.0% with respect to the peak area 100 of the compound (A).

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The thiol-containing composition for an optical material of the present invention includes a compound (A) represented by General Formula (a), and a compound (B) composed of at least one selected from a compound (b2-1) represented by General Formula (b2-1), a compound (b3-1) represented by General Formula (b3-1), a compound (b3-2) represented by General Formula (b3-2), and a compound (b4-2) represented by General Formula (b4-2), in which, in high-performance liquid chromatography measurement, the total peak area ratio of the compound included in the compound (B) is 0.1% to 60.0% with respect to the peak area 100 of the compound (A). ##STR00001##

Provided are gel particles each having a three-dimensional crosslinked structure including at least one bond selected from a urethane bond and a urea bond, the gel particles each including: a polymerizable group; and a functional group that generates radicals by irradiation with active energy rays, a photosensitive composition containing the gel particles, an ink composition, a method of producing water dispersion of gel particles, and an image forming method.