Magnetically sealing valve device for a battery casing

The apparatus has valve closing element (6) that closes housing opening (3) in closed position in pressure-tight manner and opens in an open position, so that fluids escape from an inner space (5) of housing. A magnetic field producer fixes closing element in closed position in pressure-sealing manner until the predetermined excess pressure in the inner space of the housing is reached, and upon achieving or exceeding the predetermined excess pressure, so that the change of the closing element into open position is permitted.