Provided is a pattern forming method making it possible to obtain a pattern with less scums and watermark defects. The pattern forming method includes the steps of forming a film from an actinic-ray- or radiation-sensitive resin composition includes a resin (A) that exhibits an increased solubility in an alkali developer when acted on by an acid, a compound (B) that generates an acid when exposed to actinic rays or radiation, and a resin (C) containing at least one of a fluorine atom and a silicon atom, exposing the film to light, and developing the exposed film using a tetramethylammonium hydroxide solution whose concentration is less than 2.38 mass %.