A method for removing a foreign substance according to an embodiment includes: a step of preparing a Fabry-Perot interference filter in which a gap is formed between a portion of a first laminate at least including a first mirror portion and a portion of a second laminate at least including a second mirror portion facing each other so that a distance between the first mirror portion and the second mirror portion facing each other varies by an electrostatic force; a step of detecting a foreign substance adhering to a surface of the second laminate; and a step of blowing air in which an airflow peak position is adjusted on the basis of a position of the detected foreign substance onto the surface of the second laminate and thereby removing the foreign substance from the surface of the second laminate.