A wafer holding unit includes a disk-shaped ceramic substrate having a wafer mounting surface on an upper surface of the substrate, an RF electrode, for example, embedded within the substrate, a metal terminal inserted from a lower surface of the substrate, and a connecting terminal which electrically connects the RF electrode and the metal terminal with each other. The connecting terminal is constituted by a ceramic member and a metal layer. The ceramic member is made of the same material as the substrate and preferably has a truncated conical shape. The metal layer covers a surface of the ceramic member. An upper end of the metal layer is connected to the RF electrode, while a lower end of the metal layer is connected to the metal terminal with a metal member interposed therebetween.