A cell identifier allocation method includes: a measurement step of measuring the reception power or propagation loss of the signal received inside the target cell from each of the cells of adjacent base stations in the neighborhood of the target cell; an identification step of identifying the first cell that has the greatest reception power or the lowest propagation loss, from among the cells of the adjacent base stations; and, an allocation step of allocating a cell identifier in which the code sequence number of the synchronization signal is different from that of the first cell and that has not been allocated to any of the cells of the adjacent base stations, to the target cell.