The medical device includes an insertion portion formed to have an elongated shape that can be inserted into an insertion hole of an insertion assisting tool for assisting insertion of the subject into the body cavity, and an insertion portion formed by inserting light supplied from the light source into the distal end of the insertion portion A light guide member which is provided in the insertion portion and is provided in the insertion portion and interlocked with the insertion state of the insertion portion with respect to the insertion hole and capable of emitting light forward of the distal end portion of the insertion portion, And an interlock mechanism configured to shift to any one of a state in which light can not be emitted forward and a state in which light can not be emitted forward.医療用デバイスは、被検体の体腔内への挿入を補助する挿入補助具の挿通孔に挿通可能な細長形状を具備して形成された挿入部と、光源から供給される光を挿入部の先端部へ導光する導光部材と、挿入部に設けられ、挿通孔に対する挿入部の挿通状態に連動し、挿入部の先端部より前方へ光を出射可能な状態、または、挿入部の先端部より前方へ光を出射不可能な状態のいずれかに移行するように構成されたインターロック機構と、を有する。
