A fingerprint sensor for sensing fingerprint information of a finger is provided. The fingerprint sensor includes a sensing array including a plurality of sensing units, an insulating surface disposed on the sensing array, a readout module, a memory array including a plurality of memory units respectively corresponding to the sensing units, and a processor. Each of the sensing units includes a sensing electrode. The readout module reads a sensing voltage of the sensing electrode of each of the sensing units, and provides a sensing output according to the sensing voltage. Each of the memory units is adjacent to the corresponding sensing unit and stores information of the corresponding sensing unit. The processor obtains the fingerprint information of the finger according to the sensing output and the information stored in the memory unit.