Provided is a storage system including a decoupling device having a plurality of unit capacitors. The storage system includes a storage device, a control device, and a decoupling device disposed on a circuit substrate. The storage device is configured to receive and store data from the control device. The control device is configured to generate an inner voltage. The decoupling device is connected to the control device and decouples the inner voltage. The decoupling device includes a plurality of unit capacitors constituting a plurality of decoupling capacitors. Each of the unit capacitors includes a plurality of capacitor elements, a first terminal, and a second terminal. Some of the unit capacitors are selectively connected with each other to constitute the decoupling capacitors having various capacitances.