To omit a series of operations comprising detachment of release paper, adhesion and fixation of a strip-shaped deaerating means and reattachment of the release paper and to simplify an operation associated with arrangement of a strip-shaped deaerating means, while avoiding transient external exposure of an adhesive layer.

A release material (8) is made of a sheet or a film which has a downside surface layer forming a fine ventilation channel with a surface to be waterproofed when contacting with the surface to be waterproofed. In the release material, a cutting-plane line or a notch (10) capable of being separated with fingers is formed in a strip zone corresponding to a contour of the strip-shaped deaerating means. The strip-shaped deaerating means for preventing the swelling of the waterproof sheet (1) is formed between the surface to be waterproofed and the adhesive layer by a remaining strip zone (3) of the release material remained on an adhesive surface by the separation of the release material from the adhesive layer (7).