A surface shape measuring device includes a camera that captures the observation image acquired by the optical head, a drive unit that causes the optical head to scan relatively in a scanning direction perpendicular to the measurement target, an encoder for detecting a position of the optical head in the scanning direction with respect to the measurement target, an imaging instructing unit that instructs the camera to capture the observation image based on a position signal output from the encoder for each predetermined interval, a frame dropping occurrence rate calculating unit that calculates a frame dropping occurrence rate indicating an occurrence rate of frame dropping of the camera, and a measurement condition setting unit that sets a measurement condition for measuring a surface shape of the measurement target based on the frame dropping occurrence rate.