A contact detecting apparatus detects contact between a body tissue and a probe for emitting illumination light onto the body tissue and receiving return light of the illumination light scattered from the body tissue. The contact detecting apparatus includes: a laser light source that emits laser light to irradiate a specified region of the body tissue via the probe; a photoelectric conversion unit that converts light received via the probe into an electric signal; and a signal processing unit that determines whether or not there is contact between a distal end of the probe and the body tissue based on whether the electric signal includes a component of a beat signal caused by interference of the return light of the laser light scattered from each of a surface of the body tissue and a surface of the distal end of the probe.