In the disclosed indicating device a plunger is normally held in a retracted, non-indicating position by a permanent magnet. An electro-magnet, upon energization, develops a flux opposing the holding flux of the permanent magnet to allow the plunger to be displaced by a spring into its indicating position. The magnetic circuit for most of the holding flux from the permanent magnet comprises a wall of magnetic material containing an aperture through which the plunger extends with a loose fit and through which it moves upon displacement by the spring. For preventing undesired displacement of the plunger out of its retracted position as a result of mechanical shocks and vibrations, there is developed on the plunger in the region where it passes through the aperture a radially-acting magnetomotive force that holds the outer periphery of the plunger in contact with a restricted portion of the internal wall of the aperture.