N-vinyl lactam-based crosslinked polymer, cosmetic, absorbent agent for ink, and absorbent composite

A N-vinyl lactam-based crosslinked polymer-containing composition, the composition comprising a N-vinyl lactam-based crosslinked polymer,

• the N-vinyl lactam-based crosslinked polymer containing:
• a structural unit derived from a N-vinyl lactam-based monomer;
• and
• a structural unit derived from a cyanuric acid structure-containing crosslinkable monomer,
• the N-vinyl lactam-based crosslinked polymer containing the structural unit derived from a cyanuric acid structure-containing crosslinkable monomer in a ratio of 0.12 to 0.48 mol % to 100 mol % of all structural units,
• the composition having a proportion of a compound represented by the following formula (3) of 2 mass % or less in 100 mass % of the N-vinyl lactam-based crosslinked polymer:
• wherein R4 represents a hydrogen atom or an optionally substituted C1-C10 alkyl group;
• and y represents an integer of 1 to 3.