A switching device adapted to be installed behind an opaque wall (32) so as not to be visible from the outside of the wall and intended to switch at least one electrical device (44) on. This switching device includes a first module (10) and a second module (12) adapted to make the connection between the device and a power source. The first module includes a capacitive sensor (16) having a capacitor on a printed circuit board adapted to change its capacitance value when the hand (34) of a user on the outside is placed near the wall where the device is installed. The capacitor is included in a metal frame whose function is to define the capacitive field due to the capacitor in the plane of the board and to maximize this field perpendicular to the plane of the board.