An input detecting apparatus, method in a switching matrix in which a plurality of switches are provided in the form of a matrix, which discriminates a sneak pass signal current caused by overlapping keying of up to 10 switches and is provided with a switching matrix including a driver circuit, a detecting circuit, a first group of a plurality of lines (1.sub.0 -1.sub.6), each connected to the driver circuit (2), a second group of a plurality of lines (3.sub.0 -3.sub.6), each connected to the detecting circuit, and a plurality of switching devices including a resistor (6) and a switching element (5) serially arranged, one end of each switching device being connected to one of the first group of lines and the other end to one of the second group of lines, the driver circuit having a decoder (11) which in turn connects one end of each oen of the plurality of lines of the first group (1.sub.0 -1.sub.6 ) to an electrical source having 0 voltage, one by one, the detecting circuit having a selector ( 7) selectively connecting in turn one end of the plurality of lines of the second group (3.sub.0 -3.sub.6) to a voltage detecting circuit thereof, the rest of the end of the plurality lines of the second group being connected to a decoder in which the ends of the plurality lines of the second group are in turn opened in synchronization with the operation of the selector, and a means is provided for applying a predetermined voltage higher than the detecting voltage to detect the switching operation.