Provided are a sheet processing device and a sheet manufacturing apparatus capable of removing color material from printed parts without excess or deficiency. A sheet processing device has a detector configured to detect a printed part printed on a sheet; and an eraser configured to selectively remove at least a surface part of a printed area including the printed part detected by the detector. The eraser includes a grinding tool to grind the sheet, and a pressure mechanism configured to selectively increase contact pressure between the sheet and the grinding tool in the printed area.