A fixing device for fixing an elastic sheet and a low-stretchable sheet via fixing parts while superposing the sheets in a thickness direction includes: a rotating member including protrusions on an outer peripheral surface to form the fixing parts and rotatable along a transport direction; and a sandwiching member arranged at a predetermined position of the rotating member in a rotational direction, and sandwiching the sheets by a surface portion in cooperation with each of the protrusions to form the fixing parts when each of the protrusions passes through the predetermined position, the surface portion being larger than a top surface of each of the protrusions. At a sandwiching position in which the sheets are sandwiched cooperatively by the sandwiching member and the rotating member, the low-stretchable sheet is located between the elastic sheet and the top surface of each of the protrusions of the rotating member.