A disc-shaped optical data recording medium has a signal recording layer for reading and/or writing data using light, and a 10 .mu.m to 200 .mu.m thick transparent protective layer disposed over the signal recording layer. The optical data recording medium includes a protrusion projecting from a surface of the transparent protective layer on a light-incidence surface side to which light is emitted to the signal recording layer. The protrusion is disposed in an area between a center hole and a clamping area where the optical data recording medium is held when reading and/or writing data in the signal recording layer.