An apparatus for recording/reproducing holographic data and a method of adjusting a position of a recording layer. While an objective lens focusing first and second lights having different wavelengths on a holographic data storage medium including first and second reflective layers reciprocatingly moves in a direction of an optical axis, a focus movement unit, which moves a focus of the second light in the direction of the optical axis until a time difference between a first detection signal generated when the first light is reflected from the first reflective layer and a second detection signal generated when the second light is reflected from the second reflective layer becomes a value corresponding to a position of a desired recording layer, is controlled to move a focal position of the second light so that the focal position of the second light can be adjusted to the position of a desired recording layer.