An oil for a carbon fiber precursor acrylic fiber including: a hydroxybenzoate ester (A) indicated by formula (1a); an amino-modified silicone (H) indicated by formula (3e); and an organic compound (X) which is compatible with the hydroxybenzoate ester (A), in which a residual mass rate R1 at 300° C. in thermal mass analysis in an air atmosphere is 70-100 mass % inclusive, and which is a liquid at 100° C., and a carbon fiber precursor acrylic fiber bundle to which the oil for a carbon fiber precursor acrylic fiber is adhered.