To provide a surface treating apparatus for a wafer which can uniformly and homogeneously conduct the surface treatment of the wafer with high production efficiency.

Electrode plates 5 to 9 are rotated while injecting process gas from the pores 4a of a cylinder 4, and the wafers W supplied to the outer peripheral edges of the plates 5 to 9 are uniformly and homogeneously film- formed. The wafers W are supplied to the plates 5 to 9 by a conveying robot 23 in the state that the first gate valve 17 is opened, and the film formed wafer is discharged externally via a second gate valve 20, untreated wafer is supplied to a load locking chamber 3, and wafer W is similarly supplied to the plates 5 to 9 via the robot 23 to conduct the film forming action.