A memory device includes a data memory array, a reference memory array and a detection circuit. The reference memory array includes (N/2+1) bit lines, (N/2) source lines and reference cells, N being a positive even integer. Each row of reference cells includes a (2n−1)th reference cell and a (2n)th reference cell. The (2n−1)th reference cell includes a first terminal coupled to an nth bit line, and a second terminal coupled to an nth source line, n being a positive integer less than N/2+1. The (2n)th reference cell includes a first terminal coupled to an (n+1)th bit line, and a second terminal coupled to the nth source line. The detection circuit compares a data current outputted from the data memory array and a reference current outputted from the reference memory array to determine a data state of a memory cell.