An ether polymer satisfies 5m/n1000, n denoting a mass of the ether polymer in units of g, and m denoting a mass of a first substance in units of g. The first substance is obtained by adding the ether polymer to a first solvent at 45 C. to form an ether polymer system, which is allowed to stand at 45 C. for 8 h and then at 25 C. for 24 h, and filtered through a 200-mesh filter, leaving a filter-out substance as the first substance.

Provided is an optical article having a substrate, a primer layer generated by curing a polymerizable composition for forming the primer layer, and a photochromic layer containing a photochromic compound in this order, in which the polymerizable composition for forming the primer layer contains a component A: a polyisocyanate, a component B: a hydroxy group-containing polymerizable compound, and a component C: a polymerizable compound having a viscosity of 100 cP or less and being selected from the group consisting of (meth)acrylates and vinyl ethers.

Provided is an optical article having a substrate, a primer layer generated by curing a polymerizable composition for forming the primer layer, and a photochromic layer containing a photochromic compound in this order, in which the polymerizable composition for forming the primer layer contains a component A: a polyisocyanate, a component B: a hydroxy group-containing polymerizable compound, and a component C: a polymerizable compound having a viscosity of 100 cP or less and being selected from the group consisting of (meth)acrylates and vinyl ethers.