An optical coherent cross-sectional image forming apparatus in which light outputted from a light source is divided into a measurement light and a reference light inside the apparatus and in which a cross-sectional image is formed based on a coherent light, produced from a reflected light obtained by emitting the measurement light to a biological tissue through a probe inserted into a body lumen, and the reference light, wherein the apparatus includes a detector for detecting that a transmitting and receiving unit entered inside a guiding catheter for guiding the probe by using data during the axial-direction movement and a controller for stopping at least a portion of a process associated with from generation to holding of the cross-sectional image based on the optical coherence in a case in which it is detected by the detector that the transmitting and receiving unit entered inside the guiding catheter.
