A double-side polishing apparatus for a work according to the present invention includes one or more work thickness measuring devices and a control unit. The double-side polishing method for a work includes the steps of: first polishing for polishing both surfaces of the work; first measurement for measuring the thickness of the work; in the first measurement step, when the thickness of the work is found to reach the predetermined thickness, terminating the orbital motion of the carrier plate; second polishing both surfaces of the work while the carrier plate performs only rotational motion; second measurement for measuring the thickness of the work at predetermined position(s); and determining a time for terminating polishing based on the result of the measurement of the thickness of the work in the second measurement step.