While improving the frequency characteristics of a decoupling capacitor, suppressing the voltage drop of a source line and stabilizing it, the semiconductor device which suppressed decline in the area efficiency of decoupling capacitor arrangement is offered. Decoupling capacitors DM1 and DM2 are connected between the source line connected to the pad for high-speed circuits which supplies electric power to circuit block C1, and the ground line connected to a ground pad, and the capacitor array for high-speed circuits is formed. A plurality of decoupling capacitor DM1 are connected between the source line connected to the pad for low-speed circuits which supplies electric power to circuit block C2, and the ground line connected to a ground pad, and the capacitor array for low-speed circuits is formed. Decoupling capacitor DM1 differs in the dimension of a gate electrode from DM2.