A position detection apparatus (100) which detects a position of an object includes a scale (2) including a periodic pattern, a detector (7) configured to be movable relative to the scale, and a signal processor (101) configured to acquire position information of the object based on a first output signal from the detector and perform abnormality determination based on a second output signal from the detector, a spatial frequency response of the first output signal is peaked at a first spatial frequency, and a spatial frequency response of the second output signal is peaked at a second spatial frequency different from the first spatial frequency.