Abstract: A golf putting practice device is provided including an elongated base sheet of material forming a putting surface and a pair of retaining walls adapted for assembly with the putting surface sheet. The putting surface or base sheet is formed with slots configured to maintain the retaining walls in a desired relative position to the putting surface. Each of the two retaining walls is formed from a flexible material that can be formed into the desired configuration and include an integrally formed upstanding wall member and base flange. When the retaining walls are assembled with the base sheet, the base flange underlies the putting surface and the walls project upwardly through the respective slots. The one retaining wall is of a key-hole type configuration providing a degree of retention for a golf ball and thus simulates the cup of a putting green.