A composite web 10 including an elastically stretchable web and an inelastically stretchable web bonded together is stretched on a course defined between at least two nip roll pairs 31, 32 to obtain an elastically stretchable composite sheet 20. The composite web 10 is brought into contact with a peripheral surface of at least one roll of each nip roll pair 31, 32 over an area of the peripheral surface defined by a quadrant of this roll's circular cross section.