According to one embodiment, a pattern forming method includes forming a self-assembled material on a plurality of first patterns, forming a plurality of second patterns by heating the self-assembled material and causing microphase separation of the self-assembled material, the second patterns corresponding to the first patterns, and calculating positional deviations of respective positions of the second patterns from positions of the corresponding first patterns. When at least one of the positional deviations is larger than a predetermined value, the self-assembled material is adjusted.