The invention concerns an oscillator for a timepiece movement, comprising a staff rigidly connected to a balance carrying first and second bipolar magnets spaced apart from the staff and capable, depending on the angular position of the balance, of being positioned alternately within range of a magnetic field produced by a fixed bipolar magnet, the latter being located on the trajectory of the first and second bipolar magnets and being arranged in such a way that, when one of the bipolar magnets approaches the fixed bipolar magnet, identical polarities are located opposite each other in order to produce a repulsive force. The oscillator further comprises a pallet assembly and an escape wheel for establishing a kinematic connection between a source of energy of the timepiece movement and the balance staff, and arranged in such a way that the balance is capable of having a sustained periodic oscillating movement of an amplitude greater than 90 degrees.