The present invention provides a hard-coat-layer-forming composition whereby a hard coat layer having excellent scratch resistance and cracking resistance can be formed, and an optical member. The hard-coat-layer-forming composition is a composition used to form a hard coat layer on a plastic substrate, and includes: metal oxide particles; at least one type of component X selected from the group consisting of an organic silicon compound represented by a predetermined formula, a hydrolysate thereof, and a hydrolytic condensate thereof; and at least one type of component Y selected from the group consisting of an organic silicon compound represented by a predetermined formula, a hydrolysate thereof, and a hydrolytic condensate thereof, and a glycoluril crosslinking agent, a hydrolysate thereof, and a hydrolytic condensate thereof.