Balgerij is a location on the island of Kaag, situated on the Grote Sloot in the Netherlands. It is best known as the address of the Kagermolen, a historic hollow post mill dating from the 17th century.

The mill features a distinctive red upper house and underwent a complete restoration in 1965. The area sits within the Kaag en Braassem region, a landscape characterized by polders, waterways, and traditional Dutch windmills.