An authentication system comprises a host computer; and a non-volatile memory that includes a memory cell array including a plurality of memory cells are arranged in array, the plurality of memory cells including: a memory cell in a variable state, in which a resistance value reversibly changes between a plurality of changeable resistance value ranges in accordance with an electric signal applied; and a memory cell in an initial state which does not change to the variable state unless a forming stress for changing the memory cell in the initial state to the variable state is applied thereto, a resistance value of the memory cell in the initial state being within an initial resistance value range which does not overlap with the plurality of changeable resistance value ranges, wherein in the memory cell array, data including first authentication data is stored on the basis of whether each of the plurality of memory cells is in the initial state or the variable state, wherein at least one of the host computer and the non-volatile memory stores second authentication data, and wherein at least one of the host computer and the non-volatile memory is operative to perform authentication on the basis of the first authentication data and the second authentication data.