Method for quality control of mechanical pieces, such as screws, pins, pivots and similar, intended for mass-production mechanical industries such as automobile and household appliances industries and similar, by means of an apparatus comprising in casings a plurality of operation stations and a piece-holder table which is pitched revolving to convey the pieces to the operation stations. The method comprises: subdividing the operation stations into two groups, a first group comprising fast operation stations with operation times shorter than a predetermined time, and a second group comprising slow operation stations With operation times longer than a predetermined time; providing, for each slow operation station of the second group of slow stations an equal slow operation station angularly distanced by an uneven number of pitches; stopping the piece-holder table at each pitch alternately with said operation times shorter or longer than said predetermined time; deactivating all the slow operation stations during the operation time shorter than the predetermined time. Also a quality control apparatus is disclosed.