A probe shape detection apparatus includes a magnetic field sensing section adapted to sense a magnetic field generated by an electromagnetic coil in a flexible probe, a coordinate computation section adapted to calculate three-dimensional coordinates of the electromagnetic coil based on the sensed magnetic field, a movement speed calculation section adapted to calculate a movement speed of the electromagnetic coil based on the calculated three-dimensional coordinates, a moving average coordinate calculation section adapted to calculate moving average coordinates of the electromagnetic coil, and a coil coordinate setting section adapted to make a setting so as to use one of the moving average coordinates and the three-dimensional coordinates calculated by the coordinate computation section as the three-dimensional coordinates of the electromagnetic coil, based on a comparison result of the calculated moving speed.
