Applying a writing voltage pulse having a first polarity to a metal oxide layer (3) to change a resistance state of the metal oxide layer (3) from high to low so as to render the resistance state a write state, applying an erasing voltage pulse having a second polarity different from the first polarity to the metal oxide layer (3) to change the resistance state of the metal oxide layer (3) from low to high so as to render the resistance state an erase state, and applying an initial voltage pulse having the second polarity to the metal oxide layer (3) before the applying of a writing voltage pulse is performed for a first time, to change a resistance value of an initial state of the metal oxide layer (3) are included, and R0>RH>RL and |V0|>|Ve|≧|Vw| are satisfied where R0, RL, and RH are the resistance values of the initial, write, and erase states, respectively, of the metal oxide layer (3), and V0, Vw, and Ve are voltage values of the initial, writing, and erasing voltage pulses, respectively.