A displacement measuring apparatus 100 which measures a displacement amount of a moving object 102 includes a light source that irradiates the moving object 102 using luminous flux emitted from a light emitting area 101, a photo diode array 104, 105 that includes a plurality of light receiving areas in a movement direction of the moving object 102 and that forms an image of the luminous flux reflected on a plurality of indentations 103 of the moving object 102 to receive light, and a measurement unit that measures the displacement amount of the moving object 102 based on a movement amount of a light emitting area image 106 that is formed on the photo diode array 104, 105 by forming the image of the luminous flux.