To provide a microscale displacement detection apparatus in which light from a laser light source is reflected by an object to be measured and the reflected light is received by a light receiving element wherein a concave mirror which collects the reflected light from the object to be measured easily and surely is provided on the object to be measured.

The apparatus allows the light from the laser light source 20 to be projected onto a cantilever 16 of an atomic force microscope as the object to be measured and allows the reflected light to be received by a two-part split detector 23. A microscale concave section is directly formed on the projected position of the light on the back 22 of the cantilever 16. The concave section includes a normal concave mirror, a Fresnel concave mirror, a concave diffraction grating of which the groove angle is an acute angle, a concave diffraction grating of which the groove angle is a right angle. The concave mirror can be formed by the focused ion beam method, the etching method, or the like.