Disclosed are a method and a device for determining a cell identifier. A method for determining a cell identifier can comprise the steps of: a network control unit generating an Nth neighbor cell list which comprises information about a neighboring cell of a search cell; the network control unit receiving, from a search cell, information about a global cell identifier and a first PCI of an unknown cell; the network control unit determining whether or not the unknown cell is a moving cell on the basis of the global cell identifier; and, if the unknown cell is a moving cell and the first PCI and a second PCI of a neighbor cell that is comprised in the Nth neighbor cell list, the network control unit transmitting to the moving cell a PCI change signal that requests changing of the first PCI.