A system for detecting a travel state of a capsule endoscope includes a capsule endoscope (2) containing a permanent magnet and a travel state detector (3) for detecting a position of the capsule endscope (2) based on an intensity of a constant magnetic field generated by the permanent magnet contained in the capsule emdoscope (2). The travel state detector (3) includes magnetic field detectors (6a-6h), fixing members (7a, 7b) for fixing the magnetic field detector (6a-6h) to the body of the subject, a travel state processor (8) for calculating a distance between the capsule endoscope (2) and each of the magnetic field detectors (6a-6h) based on intensities of magnetic fields detected by the magnetic field detectors (6a-6h), deriving the position and orientation direction of the capsule endoscope (2), and determining the travel state of the capsule endoscope (2) based on a result of derivation.
