A pattern forming method in an embodiment includes forming, on or above a substrate, a block copolymer layer containing a first polymer and a second polymer having lower surface energy than the first polymer, heat treating the block copolymer layer to separate the block copolymer layer into a first phase containing the first polymer and a second phase containing the second polymer, and using an atomic layer deposition process, selectively forming a metal layer on the first phase and selectively removing the second phase.