A navigation system includes a luminal organ extraction unit (31) configured to extract a luminal organ from image information about a subject acquired in advance, a branch conduit extraction unit (32) configured to extract a branch conduit from the luminal organ, an alignment unit (24) and a coordinate transformation unit (25) configured to align position information of a viewpoint acquired inside the subject with the extracted luminal organ and to generate corrected position information, a determination unit (26) configured to determine performance/non-performance of observation of the branch conduit based on the corrected position information, a target setting unit (33) configured to set one of unobserved branch conduits as a target branch conduit, and a navigation information generation unit (34) configured to cause the target branch conduit to be updated in a case where the target branch conduit is observed, and to generate navigation information.
