Provided is a method of forming fine patterns capable of minimizing LER and LWR to form high quality nanopatterns, by using a block copolymer having excellent etching selectivity. Provided is a block copolymer comprising a first block having a repeating unit represented by the following Chemical Formula 1, and a second block having a repeating unit represented by the following Chemical Formula 2: [Image]
[Chemical Formula 2] [Image] wherein R1 to R5, X1 to X5, l, n and m are as defined in claim 1.