In a method of producing a composite sheet 3S having stretchability, the producing including joining a first sheet 1S in which stretchability in a longitudinal direction of the first sheet 1S is developed by being subjected to a drawing process in the longitudinal direction and a second sheet 2S having stretchability in a longitudinal direction of the second sheet that is lower than the stretchability of the first sheet, the longitudinal directions being aligned with each other, a mismatch in a width dimension of the first sheet 1S and the second sheet 2S is alleviated. The first sheet 1S is extended in the longitudinal direction of the first sheet, while transporting the first sheet 1S in the longitudinal direction of the first sheet 1S with the first sheet being in contact with an upstream roll and a downstream roll that rotate adjacent to each other, by providing a difference in peripheral speeds between the upstream roll 31 and the downstream roll 41, and the second sheet 2S is joined to a portion of the first sheet 1S in an overlapped manner, the portion being in contact with the downstream roll 41 in the extended state.
