A medical tube position confirmation system for confirming the position of a medical tube that is used to supply nutrients to the interior of a body by means of tube feeding while an end portion thereof is inserted into (placed in) the stomach includes a light guide that is configured to guide light entering through an incident end portion so that the light exits through an exit end portion, and is configured to be insertable into the medical tube so that the exit end portion is disposed in the interior of the stomach, a light source that is optically connected to the incident end portion of the light guide and emits light containing wavelengths that pass through a living body, and a control unit that controls intensity of light emitted by the light source, wherein the control unit controls the intensity of light emitted by the light source within an intensity range that equals or exceeds a first intensity specific to a patient and is lower than a second intensity specific to the patient.

A tube distal end position detection system (1) includes a light source device (50) that emits light, a hollow tube (10) having a flow path (11) that allows a liquid to flow through, a connector (20) provided at a base end of the tube so as to allow light from the light source device to be incident on an end surface (12) at the base end of the tube, and a light emitting portion (30) provided at the distal end of the tube. Light from the light source device passes through the tube and is emitted from the light emitting portion and transmitted to the body surface.