A position detecting device includes a first bias magnet and a second bias magnet and a detecting element configured to detect a direction of a magnetic field generated by the first magnet and the second magnet. The first magnet and the second magnet are disposed with magnetic poles thereof having the same polarity arranged opposing each other. The direction of the magnetic field detected by the detecting element changes when an object to be detected D moves in an opposing direction between the first magnet and the second magnet.