This disclosure provides an information recording device for use in a non-volatile information recording/reproduction system having a high recording density, the device including a resistive material having less phase separation or the like during switching. This disclosure also provides an information recording/reproduction system including the device. This disclosure provides an information recording device including: a pair of electrodes; and a recording layer between the electrodes, the recording layer recording information by its resistance change, the recording layer including at least one of (a) M3Oz and (b) AxM3—x0z as a main component, in (a) and (b), z being a value representing oxygen deficiency from z=4.5, and in (b), x satisfying 0.00