The present inventors identified a selective marker 65B13 for GABA neuron progenitor cells of the spinal dorsal horn and cerebellum, and successfully isolated GABA neuron progenitor cells using antibodies that bind to a protein encoded by the gene. 65B13 was demonstrated to be useful as a marker to isolate GABA-producing neuron progenitor cells in the spinal dorsal horn and cerebellum. GABA neuron progenitor cells can be efficiently identified or isolated by using the identified marker as an indicator.