A mother-baby endoscope includes: a lateral-view mother endoscope housing a treatment instrument raising stand in a distal end portion and including a treatment instrument insertion channel disposed in an insertion portion and opening toward the treatment instrument raising stand and a baby endoscope including an insertion portion having a bending portion disposed on a distal end side, the insertion portion being inserted into the treatment instrument insertion channel of the mother endoscope and guided into a body cavity for observing or treating a region to be inspected. When the insertion portion of the baby endoscope is protruded by approximately 20 millimeters from an observation window of the mother endoscope in an observation direction, a proximal end surface of the bending portion of the baby endoscope is set to be located on a more proximal end side than an opening portion of the treatment instrument insertion channel.
