A random number generating apparatus comprising: a memory cell (91, M211 to M233) including a variable resistance element, the memory cell (91, M211 to M233) being shiftable from an initial state to a variable state by applying a forming stress that is an electric signal to the memory cell (91, M211 to M233); wherein the variable resistance element (i) has a resistance value in an initial resistance value range in the initial state, and (ii) has a resistance value in a first resistance value range or a second resistance value range in the variable state, wherein the initial resistance value range does not overlap any of the first and second resistance value ranges, wherein the resistance value shifts from the second resistance value range to the first resistance value range higher than the second resistance value range when a first electric signal is applied to the memory cell (91, M211 to M233), and shifts from the first resistance value range to the second resistance value range when a second electric signal different from the first electric signal is applied to the memory cell (91, M211 to M233); the resistance value of the variable resistance element randomly changes over time within one of the first resistance value range and the second resistance value range, while the memory cell is in the variable state, even though the first and the second electric signals are not applied; and the random number generating apparatus further includes a control circuitry adapted for obtaining a plurality of items of resistance value information, at a plurality of different times, from the variable resistance element while the memory cell (91, M211 to M233) is in one of the first resistance value range and the second resistance value range in which the resistance value randomly changes over time; the random number generating apparatus further comprises a determination circuitry adapted for determining a magnitude relation between two of the plurality of items of resistance value information; and a generator adapted for generating random number data on the basis of a determination result of the determination circuitry. a memory cell (91, M211 to M233) including a variable resistance element, the memory cell (91, M211 to M233) being shiftable from an initial state to a variable state by applying a forming stress that is an electric signal to the memory cell (91, M211 to M233); wherein the variable resistance element (i) has a resistance value in an initial resistance value range in the initial state, and (ii) has a resistance value in a first resistance value range or a second resistance value range in the variable state, wherein the initial resistance value range does not overlap any of the first and second resistance value ranges, wherein the resistance value shifts from the second resistance value range to the first resistance value range higher than the second resistance value range when a first electric signal is applied to the memory cell (91, M211 to M233), and shifts from the first resistance value range to the second resistance value range when a second electric signal different from the first electric signal is applied to the memory cell (91, M211 to M233); the resistance value of the variable resistance element randomly changes over time within one of the first resistance value range and the second resistance value range, while the memory cell is in the variable state, even though the first and the second electric signals are not applied; and the random number generating apparatus further includes a control circuitry adapted for obtaining a plurality of items of resistance value information, at a plurality of different times, from the variable resistance element while the memory cell (91, M211 to M233) is in one of the first resistance value range and the second resistance value range in which the resistance value randomly changes over time; the random number generating apparatus further comprises a determination circuitry adapted for determining a magnitude relation between two of the plurality of items of resistance value information; and a generator adapted for generating random number data on the basis of a determination result of the determination circuitry.