A thin electromagnetic handwriting pen includes a casing unit, a circuit unit, an electromagnetic unit and a pen core unit. The casing unit includes a thin pen-shaped casing structure. The circuit unit includes a circuit substrate disposed inside the thin pen-shaped casing structure. The electromagnetic unit includes a hollow holder and an electromagnetic coil wound around the hollow holder. Both the hollow holder and the electromagnetic coil are embedded in the thin pen-shaped casing structure, and the electromagnetic coil is fixed between the thin pen-shaped casing structure and the hollow holder and electrically connected to the circuit substrate. The pen core unit includes a pen core structure movably disposed inside the thin pen-shaped casing structure and passing through the hollow holder, and one portion of the pen core structure is exposed outside the thin pen-shaped casing structure.