An aliphatic ketone polymer comprising a unit represented by the following formula (1), the unit represented by the following formula (2), and a unit represented by the following formula (3) or (4). (In the formulae, R1 to R10 may be the same or different and each represents hydrogen, an optionally halogenated C1-20 hydrocarbon group, halogeno, hydroxy, ester, alkoxy, cyano, imide, silyl, or a group selected from the group consisting of C1-20 hydrocarbon groups substituted by a functional group selected among hydroxy, ester, alkoxy, cyano, imide, and silyl, provided that R2 and R8 may be bonded to R3 and R9, respectively, to form a monocycle or polycycle; and n1, n2, and N3 satisfy 1≦n1≦20, 1≦n2≦35,000, and 1≦n3≦40,000.)