A decoupling circuit includes an inverter. The inverter includes i (i is an integer of 1 or more) PMOS transistors each having a first gate electrode, and j (j is an integer of 0 or more) PMOS transistors each having a second gate electrode. The inverter includes m (m is an integer of 1 or more) NMOS transistors each having a third gate electrode, and n (n is an integer of 0 or more) NMOS transistors each having a fourth gate electrode. The first to fourth gate electrodes are coupled to an input end of the inverter. A total area of the first and second gate electrodes is different from a total area of the third and fourth gate electrodes.