An apparatus for aligning a flat zone of a wafer is provided to prevent the fabricating process from being performed in a state that wafers are abnormally positioned by aligning the flat zone of a wafer and by checking whether the wafers are abnormally aligned. A wafer(W) is supported and rotated by a chuck. A first sensor part(120) detects the flat zone of the wafer rotated by the chuck. A control part(140) controls the rotation of the chuck according to a detection signal of the flat zone of the first sensor part so as to align the wafer with respect to the flat zone of the wafer. At least one of a second sensor part detects the edge portions of the wafer to determine the align state of the aligned wafer. An alarm part(142) generates an alarm when the wafer is abnormally aligned.
