To provide a construction method of a waterproof sheet which can shorten a curing period at a job site and form a uniform waterproof layer by solving problems of the conventional methods using asphalt waterproofing, sheet waterproofing, urethane coating film waterproofing, a vinyl chloride sheet floor or the like, and a waterproof sheet used in the construction method.

A primer is applied on a floor surface in a construction site, consequently an adhesive layer is formed, and then a waterproof sheet, which is produced beforehand in a factory or the like by molding a waterproof sheet comprising a top coat layer and an urethane waterproof layer in a recessed mold form, is laid all over the adhesive layer to form a waterproof layer on the floor surface.