A polymerizable composition for giving a resin which has a high refractive index and low dispersion and is excellent especially in impact resistance and dyeability; and a resin and an optical part each obtained by curing the composition. The polymerizable composition comprises (A) the compound(s) represented by the formula (1) and/or formula (2), one or more compounds as the following ingredient (B), and one or more compounds as the following ingredient (C). [Chemical formula 1] (1) [Chemical formula 2] (2) Ingredient (B): polythiol compound(s) optionally containing one or more (poly)sulfide bonds per molecule. Ingredient (C): compound(s) represented by the formula (3): HO-[R1-(Y)n]m-R2-X (3) (wherein X represents OH or SH; Y represents oxygen or sulfur; R1 and R2 each independently represents optionally substituted methylene or optionally substituted C2-4 alkylene; n is 0 or 1 when Y is oxygen, and is an integer of 0 to 2 when Y is sulfur; and m is an integer of 0 to 3, provided that [(carbon number of R1)+n]×m+(carbon number of R2) is 3 or larger).