A polarity-reversal protector for power sources, in particular for automobile batteries, which is connected between a power source and at least one consumer and/or at least one generator, is described. The polarity-reversal protector is to prevent the reverse polarity current from flowing through the connected systems, so that the systems may not be damaged in case of polarity reversal. For this purpose, the polarity-reversal protector includes means for recognizing whether the two poles of the power source are connected to the appropriate terminals of the consumer and/or generator, and means for decoupling the power source from the consumer and/or from the generator if the two poles of the power source have been transposed during connection to the consumer and/or generator.