Position detecting device

A position detecting device comprising:

• a scale having a magnetic signal magnetically recorded on a magnetic medium;
• and
• a magnetism detecting element comprising an element having a first and a second magnetic layer and a barrier layer sandwiched therebetween, wherein a magnetization direction of the first magnetic layer is fixed in parallel or anti-parallel with a direction along which position detection is performed, and the second magnetic layer varies a resistance value thereof by varying a magnetization direction in accordance with a quantity of a magnetic field in a direction in parallel or anti-parallel with a direction along which position detection is performed, of a leakage magnetism from the scale, and outputs a signal corresponding to a recording signal at a position where the leakage magnetism is detected;
• a bias magnetic field generation section configured to apply a bias magnetic field to the second magnetic layer and set a magnetization direction of the second magnetic layer to a direction different from the magnetization direction of the first magnetic layer in a state where there is no leakage magnetism from the scale;
• and
• a position detecting section configured to detect a position relative to the scale based on a signal corresponding to the recording signal.