Abstract: The present invention provides a method for producing a mulching sheet which easy to biodegrade and can be produced at a low cost. A cotton waste sheet is prepared with randomly accumulated cotton waste and impurities selected from a group consisting of cottonseeds, stems, leaves and calyxes of cotton tree. Water is sprayed to the cotton waste sheet. Thereafter, the cotton waste sheet is passed between a pair of calender rolls each taking a form of a Japanese drum, while being heated, to press the cotton waste sheet in the thickness direction. The cotton waste is thereby closed, and the obtained mulching sheet has a high tensile strength. Furthermore, the impurities in the cotton waste sheet are crushed or flatted. The mulching sheet is a mixture of parts made of flatted impurities and parts made of cotton waste.