A semiconductor device according to the present invention comprises a first semiconductor integrated circuit 11 having a predetermined function, the first semiconductor integrated circuit outputting a required output signal, a second semiconductor integrated circuit 12 in which a plurality of MOS elements (PMOS transistor or NMOS transistor) for independently switching to and from a conducted state and a non-conducted state in accordance with a plurality of gate signals each having a different timing is provided and the plurality of MOS elements is connected in parallel to an output or an input of the first semiconductor integrated circuit, and a pulse generating circuit 13 for generating and outputting the plurality of gate signals φi (i=1, 2, 3) each having a different timing with respect to the plurality of MOS elements in the second semiconductor integrated circuit.