An apparatus for checking for a presence of an electrically conductive body has at least one transmitting device and at least one receiving device. The transmitting device provides a transmission signal in the form of a magnetic field. The receiving device generates a reception signal from the transmission signal that is induced into the receiving device. The transmitting and receiving devices are configured in such a way that, when the electrically conductive body is absent, partial reception signals form in the receiving device on account of the induced transmission signal and the partial reception signals substantially cancel one another out in the reception signal.