To provide an electronic endoscope system capable of detecting the position of a leading edge of a flexible tube precisely irrespective of a specification of the flexible tube.

The electronic endoscope system comprises an endoscope having the flexible tube with an image sensor on the leading edge, a magnetic field generating means for generating magnetic fields at least in the first and second directions which are orthogonal with each other, a magnetic field detection means located on the leading edge of the flexible tube and having a magnetic field detection sensor for detecting the magnetic fields and for outputting a detection signal that corresponds to the magnetic field of each direction, a positional information generating means for generating relative positional information of the leading edge of the flexible tube in relation to the magnetic field generating means on the basis of the detection signal outputted from the magnetic field detection sensor, and a correction means for correcting the level of a reference detection signal, which is generated when the magnetic field generating position is separated from the magnetic field detection sensor by a predetemined distance and is inputted into the positional information generating means, to meet a predetermined condition. The positional information generating means generates the relative positional information of the leading edge of the flexible tube in a state of correction by the correction means.