This flexible tubular insertion device is provided with: a flexible tube part that is partitioned into one or more segments； one or more stiffness varying parts that vary the bending stiffness of the flexible tube part for each of the at least one segment； a state detection part that detects information relating to the curved state of the flexile tube part； a state calculation part that calculates curved shape information of the flexible tube part on the basis of the information obtained from the state detection part； a curve determination part that determines whether or not the flexible tube part is curved on the basis of the information obtained from the state calculation part； and a stiffness control part that varies bending stiffness values of the stiffness varying parts on the basis of the information obtained from the curve determination part, thereby controlling the bending stiffness of the flexible tube part for each of the at least one segment. After the curve determination part determines that a segment including a stiffness varying part is curved, the stiffness control part performs control so that the bending stiffness value of the stiffness varying part included in the segment is relatively high compared to the bending stiffness value for a side of the flexible tube part closer to the proximal end than the segment.L'invention concerne un dispositif d'insertion tubulaire souple, comportant : une partie de tube souple, qui est divisée en un ou plusieurs segments ； une ou plusieurs parties de variation de rigidité, qui font varier la rigidité à la flexion de la partie de tube souple pour chacun desdits segments ； une partie de détection d'état, qui détecte des informations relatives à l'état incurvé de la partie de tube souple ； une partie de calcul d'état, qui calcule des informations de forme incurvée de la partie de tube souple sur la base des informations obtenues à partir de la partie de détection d'état ； une partie de détermination de courbe, qui dé
