Abstract: In a method of measuring electrical analog quantities, a first analog signal representing a first electrical analog quantity which is to be a reference is subtracted from a second analog signal representing a second electrical analog quantity which is to be compared with the first analog quantity, so that a difference signal is produced. Then, the difference signal thus produced is integrated for a predetermined time to obtain a third analog signal. Simultaneously therewith, the first analog signal is also integrated for the predetermined time to obtain a fourth and a fifth analog signal representing the positive and the negative value of the aforementioned integration. And the third analog signal is integrated between it and the fifth or the fourth analog signal in accordance with the positive or the negative sign of the third analog signal to obtain a sixth analog signal.