An observation device for observing the interior of a subject of observation comprises: a light source (26) an insertion section (12) which has a light-source light emission section (22) for emitting light from the light source in the vicinity of the tip end thereof, and which is inserted into the interior of the subject of observation an imaging member (24) which is provided in the vicinity of the tip end of the insertion section, and detects the amount of visible light that is input thereto a decision section (30) which makes a decision regarding the position of the tip end of the insertion section and a control section (28) which controls the light source so as to generate, from the light-source light emission section, an omission signal that has at least light of a prescribed wavelength region omitted in the visible light and is characteristic for detection of the tip-end position of the insertion section. The imaging member outputs detection information by performing a detection operation in the period in which the omission signal is emitted, and the decision section makes a decision regarding the tip-end position of the insertion section based on this detection information.La présente invention concerne un dispositif dobservation pour observer lintérieur dun sujet dobservation qui comprend : une source de lumière (26) une section dinsertion (12) qui a une section démission de lumière de source de lumière (22) pour émettre de la lumière depuis la source de lumière à proximité de lextrémité de pointe de celle-ci, et qui est insérée à lintérieur du sujet dobservation un composant dimagerie (24) qui est disposé à proximité de lextrémité de pointe de la section dinsertion, et détecte la quantité de lumière visible qui est appliquée à celle-ci une section de décision (30) qui prend une décision concernant la position de lextrémité de pointe de la section dinsertion et une section de commande (28) qui commande la source de lumière de manière à générer, à partir d
