A scanning probe microscope is capable of radiating light on a sample without moving the sample from the scanning probe microscope and is capable of measuring the sample while controlling the conditions under which the sample is placed without changing the location of the sample. The scanning probe microscope includes a cantilever having a probe at a distal end thereof, a sample moving device for moving the sample, and a detection unit for detecting deflection of the cantilever using a laser beam. The detection unit is detachably mounted to the scanning probe microscope during measurement of the sample and is detachable from the microscope to enable radiation of the sample with light without changing the location of the sample.