A pocket protector is a sheath esigned to hold writing instruments and other small implements, such as slide rules, while preventing them from damaging the wearer's shirt pocket (e.g., by tearing or staining by a leaky pen). The pocket protector is designed to fit neatly inside the breast pocket of a man's shirt, and may accommodate pens, pencils, screwdrivers, small slide rules, and various other small items. A flap overlapping the pocket exterior helps to secure the pocket protector in place.