To enable execution of heat seal at a low temperature by a method wherein an adhesion accelerating layer constituted of a discharge treatment layer and/or of an adhesion accelerating treatment layer is provided on the heat seal side of a base sheet forming a base material of a blister.

An adhesion accelerating layer 1 constituted of a discharge treatment layer and/or of an adhesion accelerating treatment layer is provided on the heat seal side of a base sheet 4 forming a base material 2 of a blister and constituted of a sheet of polyolefin resin. The adhesion accelerating layer 1 is formed by applying discharge treatment by corona discharge treatment or plasma treatment to the base sheet 4 and/or by coating it with the adhesion accelerating treatment layer. Thereby the base material is made an energy- saving type base material which can be heat-sealed even at a low temperature, and also a cover material for which an aluminum leaf is used as a base film can be heat-sealed at a low temperature. In addition, no heat shrinkage is brought about even when the cover material for which a plastic film inferior in heat resistance is used as the base film is used.