A position detecting circuit provided in an imaging apparatus having an optical system that images a subject image, an imaging element that performs photoelectric conversion of the subject image, and a release switch capable of setting states of two stages includes: a plurality of magnetic field change detecting elements that detect the intensity of a magnetic field formed by a magnetic field generating body attached to either the optical system or the imaging element and that are provided so as to be separated from each other; a position detecting portion that detects the position of the magnetic field generating body on the basis of outputs from the plurality of magnetic field change detecting elements; and a standby portion that stops a function of at least one of the position detecting portion and the plurality of magnetic field change detecting elements until a first stage of the release switch is set.