Attachment sheet, helmet, goggles, and method for attaching anti-fog sheet

An objective of the present invention is to provide an attachment sheet that can be easily attached and is not easily removed from visor shields in helmets, lenses in goggles, and the like. An attachment sheet (10) is attached to a concavely curved surface, which is the inner wall surface of a visor shield or a goggle lens, in such a manner as to bend along the curved surface. The attachment sheet comprises: a plate-shaped base sheet (100) that is formed from a polycarbonate having a thickness of at least 0.1mm, and that, when not attached, has a smaller curvature than the surface to which the attachment sheet (10) is to be attached; and an anti-fog layer (105) that is provided to at least the surface, among both surfaces of the base sheet (100), which will not face the concavely curved surface when the attachment sheet is attached to the concavely curved surface.