A three-dimensional shape is measured by a simple system structure. A three-dimensional shape measuring instrument comprises a device (1-1) in which a light-emitting diode (1-1b) is installed as a marker in a line laser light source (1-1a), an imaging device (1-2), and a computer (1-3). For measurement, a line laser beam from the device (1-1) is applied to an object (1-4) to be measured, the imaging device (1-2) images the applied line laser beam (1-5) and the light-emitting diode, and a three-dimensional shape is obtained from the image data by triangulation by means of the computer (1-3).