Abstract: A semiconductor circuit in which propagated noise from high-speed switching is reduced even if chip size is downsized, by comprises a first circuit such as a DC-DC converter having an oscillating circuit therein, a second circuit having no oscillating circuit, a connection pad connected to a power supply, a first power line and a second power line. A first resistor is disposed on the first power line, and a second resistor, preferably of equal resistance value to that of the first resistor, is disposed on the second power line. By providing resistors on the both or at least. one of the power lines, high-frequency noise generated by the DC-DC converter and propagated to the second circuit through the power lines is reduced.