A processing module includes: a processing container including therein processing spaces in which stages are disposed, respectively, wherein a center of each of the processing spaces is located on a same circumference; a rotation arm including holders configured to hold wafers, which are placed on the stages of the processing spaces, respectively, wherein the rotation arm is rotatable around a center of the circumference as a rotation axis; and a sensor located between adjacent processing spaces and configured to detect positions of the wafers held by the rotation arm during rotational operation of the rotation arm.