To provide a ceramic base plate having split grooves capable of stably cutting out many products each having a dimension of 1.0 mm × 0.5 mm without splitting even when a load is applied to the ceramic base plate without observing occurrence of a crack at the split groove.

The ceramic base plate 1 comprises a product region S and a dummy region R at the periphery of the region S. The region R has a first dummy region T of the product region side, and a second dummy region U at an outside of the region T. Lateral and longitudinal split grooves 7, 8 are formed on the surface of the region T. Longitudinal and/or lateral cut grooves 9, 10 arriving at the outer side on an extension line of a boundary for partitioning the region T and the region U are formed on the surface of the second region U.