A displacement detection mechanism for a scanning probe microscope capable of performing measurement quickly with high precision even if an objective lens or an illumination system is arranged above or below a sample or a cantilever, and a scanning probe microscope comprising it. The displacement detection mechanism (112) for a scanning probe microscope comprising a supporting section (22) for supporting a cantilever (20), a light source (114) for irradiating a reflective surface (14) with light, and a light receiving section (121) for receiving light reflected off the reflective surface (14), and detecting displacement of the cantilever (20) based on the light receiving position of the light receiving section (121), wherein the rear end of the cantilever (20) is secured to the supporting section (22), and the above light is allowed to impinge on the reflective surface (14), while inclining toward the X axis and Y axis, from above regions B and C on the distal end side of the cantilever (20) out of regions A, B, C and D sectioned, when viewed from the above, by the Y axis extending in the longitudinal direction of the cantilever (20) and the X axis passing through the reflective surface (14) and extending in the direction intersecting the Y axis perpendicularly.