To obtain a primer composition for plastic lens capable of rapidly forming a film and improving adhesiveness and impact resistance by irradiation with ultraviolet light by making the composition include a specific polycarbonate, a specific polythiol and a specific photoinitiator.

This primer composition comprises (A) a plycarbonate of formula I [R is an unsaturated group; R' is a divalent aliphatic or aromatic; (n) is 1-9] such as trimethyleneglycolbisallyl carbonate, (B) a polythiol represented by formula II [2 is a polyvalent organic group; (m) is an integer of ≥2] such as ethylene glycolbis(thioglycolate) and (C) preferably 0.005-10 wt.% photoinitiator such as benzoin. Furthermore, the primer composition contains the components A and B at an equivalent ratio of (2/1) to (1/3), a further preferably (1.2/1) to (1/1.3). This plastic lens with a primer is preferably prepared by forming a photosetting primer layer 2 of the primer composition onto a plastic lens substrate 1.