PURPOSE: To position a substrate carried into a rotary substrate treating apparatus by a simple constitution.

CONSTITUTION: A motor-driven turn table 3 has a pin-like member 11 for supporting the back side of a substrate W and members 12 for regulating the horizontal position of the substrate W. Each regulating member 12 is rotatable round the center axis PJ and capable of oscillating round the oscillation support point YS and normally pressed toward the outer marginal edge of the substrate W by a compression coil spring 15. Below the table 3 an annular lift member 16 having a slope to displace the lower end 12b of the regulating member 12 is liftable disposed to switch the return and release of each regulating member 12 as it goes up and down. Specific regulating member 12 is driven to rotate round the axis PJ by a drive arm whereby the substrate W is rotated, relative to the regulating member 12 and any regulating member 12 is point-contacted with the original flat of the substrate W to position it.