The present invention provides a field asymmetric ion mobility spectrometer for selectively separating at least one kind of material from a mixture containing two or more kinds of materials. A filter included in the spectrometry comprises first—four plate-like electrodes each having a principal plane parallel to a direction from an ionizer toward a filter. The second plate-like electrode is located between the first plate-like electrode and the third plate-like electrode. The third plate-like electrode is located between the second plate-like electrode and the fourth plate-like electrode. The third and fourth plate-like electrodes are electrically connected to the first and second plate-like electrodes, respectively. An interspace is formed between two adjacent plate-like electrodes. The present invention provides a field asymmetric ion mobility spectrometer having high separation ability.