An optical information recording/reproduction device includes a detection unit which detects a focus-direction height of a recording medium, a focus adjustment unit which adjusts a focus-direction distance between the recording medium and a signal light optical system and a reference light system, and a control unit which controls the focus adjustment unit so that a relative distance between the object lens of the signal light optical system and the recording medium is adjusted according to the focus-direction height of the recording medium detected by the detection unit.