A wafer manufacturing method includes a wafer preparing step of preparing a wafer including a semiconductor device formed in each of a plurality of regions demarcated by a plurality of streets intersecting each other, a removing step of separating, from the wafer, a defective device region including a semiconductor device determined to be a defective product among a plurality of the semiconductor devices formed in the wafer, and a fitting step of fitting, into a through hole formed by separating the defective device region from the wafer, a device chip including a semiconductor device as a non-defective product having same functions as those of the semiconductor device determined to be a defective product and having a size capable of being fitted into the through hole.