A position detecting apparatus having a magnetic field generator that generates a position detecting magnetic field having variable strength, a position calculator that acquires magnetic information relating to the position detecting magnetic field at a position where a detected object is present, and calculates a position of the detected object based on the magnetic information, a range calculator that calculates a possible existence range in which the detected object can be present at a second time instant when a predetermined time has passed since a first time instant, based on the position of the detected object at the first time instant calculated by the position calculator, and a magnetic-field strength controller that controls a strength of the position detecting magnetic field so that the position detecting magnetic field having a strength detectable by the detected object-is generated within the possible existence range.