A method for producing a polymerizable composition, the method including: step (1) of preparing composition A having a water content of 200 ppm by mass or less, the composition A including a polyisocyanate component but not including a polymerization catalyst; step (2) of preparing composition B having a water content of 1,000 ppm by mass or less, the composition B including a polythiol component; and step (3) of mixing the composition A and the composition B and obtaining a polymerizable composition, and also a method for producing an optical component, the method including: a step of injecting the above-mentioned polymerizable composition into a molding die; and a step of polymerizing the polymerizable composition.