A contact detecting apparatus (5, 305, 405) for detecting contact between a body tissue and a measurement probe (3, 203, 303, 403) configured to emit illumination light onto the body tissue which is in contact with a distal end of the measurement probe, and to receive return light of the illumination light scattered from the body tissue, the contact detecting apparatus comprising: a laser light source configured to emit laser light having a wavelength shorter than a wavelength of the illumination light to irradiate a specified region of the body tissue via the measurement probe; a photoelectric conversion unit configured to convert light received via the measurement probe into an electric signal; and a signal processing unit configured to determine whether or not there is contact between the distal end of the measurement probe and the body tissue characterised in that the determination is based on whether the electric signal converted by the photoelectric conversion unit includes a component of a beat signal caused by Doppler effect of the return light (71, 72) of the laser light scattered from each of a surface of the body tissue and a surface of the distal end of the measurement probe due to a relative movement between the measurement probe and the surface of the body tissue, the signal processing unit is configured to determine that the distal end of the measurement probe and the body tissue move relatively to each other and are not in contact with each other if the converted electric signal includes the component of the beat signal, and is configured to determine that the distal end of the measurement probe and the body tissue do not move relatively to each other and are in contact with each other if the converted electric signal does not include the component of the beat signal. a laser light source configured to emit laser light having a wavelength shorter than a wavelength of the illumination light to irradiate a specified region of the body tissue via the measurement probe; a photoelectric conversion unit configured to convert light received via the measurement probe into an electric signal; and a signal processing unit configured to determine whether or not there is contact between the distal end of the measurement probe and the body tissue characterised in that the determination is based on whether the electric signal converted by the photoelectric conversion unit includes a component of a beat signal caused by Doppler effect of the return light (71, 72) of the laser light scattered from each of a surface of the body tissue and a surface of the distal end of the measurement probe due to a relative movement between the measurement probe and the surface of the body tissue, the signal processing unit is configured to determine that the distal end of the measurement probe and the body tissue move relatively to each other and are not in contact with each other if the converted electric signal includes the component of the beat signal, and is configured to determine that the distal end of the measurement probe and the body tissue do not move relatively to each other and are in contact with each other if the converted electric signal does not include the component of the beat signal.