To measure a surface shape accurately with a simple configuration by providing a displacement detection means for detecting the displacement of a cantilever and relatively scanning a probe along a sample surface while maintaining the displacement state of the cantilever constantly.

A displacement detection means is mounted to the tip of an actuator 10 and, as an example, a displacement sensor 12 for detecting the displacement state of a cantilever 6 optically is provided. A control system has an X control unit 14, an Y control unit 16, and Z control unit 18 for outputting a control signal to the actuator 10, maintaining the displacement state of the cantilever 6 constantly, and scanning a probe 4 in X, Y, and Z directions along a sample surface 2a based on a displacement signal that is outputted from the displacement sensor 12. The sample 2 and the probe 4 are relatively scanned and a feedback control is made when a displacement in a direction that is vertical to the scanning direction for the amount of scanning in a small range on the sample 2 exceeds a set threshold. A surface shape can be measured accurately with a simple configuration.