To provide a substrate placement member wherein erosion of an adhesive layer due to corrosive gas or plasma is hardly generated, and to provide a substrate treatment apparatus using the substrate mounting member.

In the substrate treatment apparatus wherein a substrate W is treated by corrosive gas or a plasma treatment, the substrate mounting member 3 for mounting the substrate is provided with a base member 8 which has a main metal body 8a and an insulating layer 8b for coating the periphery of the main body, an electrostatic chuck 9 for attracting the substrate which is arranged on the base member, and an adhesive layer 10 for sticking the base member 8 and the electrostatic chuck 9. The electrostatic chuck 9 is provided with a dielectric member 16 and an electrode 17 arranged in the dielectric member. The dielectric member 16 has a protrusion part 16a in the periphery which part 16a is so practically in contact with only an insulating layer 8b of the base member 8 that periphery of the adhesive layer 10 is not exposed, practically.