To provide an oily hair cosmetic containing a polyaspartic acid derivative as a basic setting agent polymer, hardly imparting greasy feeling and starchy feeling to the hair, imparting gloss thereto, and protecting the hair from thermal stimulation.

The oily hair cosmetic contains a polymer having ≥1 mol% of at least one kind of repeating unit selected from the group consisting of repeating units represented by formula (1) or (2) [wherein, R1 is a hydrogen atom or a 1-6C lower hydrocarbon group; R2 and R5 are each independently a 1-24C saturated or unsaturated hydrocarbon group; R3 and R4 are each independently a hydrogen atom or a 1-24C saturated or unsaturated hydrocarbon group; R3 and R4 may form a 6-membered ring containing a nitrogen atom by bonding them to each other].