In a sensor (11) for automatically triggering safety devices in motor vehicles, a toggle body (15) that acts as a seismic mass and that bears at one end a permanent magnet (17) is arranged inside the housing. The permanent magnet (17) is operationally connected to a Hall-effect switch (22). The toggle body (15) rests on protuberances (30) shaped in the bottom (14a) of the housing (10). The adhesion between the bottom (14) and the lower side of the toggle body (15) caused by humidity entering the housing can thus be maintained at the lowest possible level. In order to remove dirt particles from the toggling area of the toggle body (15), channels (36) that allow the dirt particles to migrate into a funnel (34) shaped in the bottom (14a) are formed in the conical area (13) of the housing recess.
