An optical recording medium drive device including: a combining prism for combining a recording first laser beam emitted from a first light source with a recording second laser beam emitted from the first light source so as to coaxially guide them; an objective lens for condensing the first and second laser beams from the combining prism toward an optical recording medium; a first photodetecting means for detecting reflected light of the first laser beam from a recording layer; a second photodetecting means for detecting reflected light of the second laser beam from a guide layer; a magnification conversion element disposed on an optical path of the second laser beam between a second light source and the combining prism for diffusing or converging the second laser beam incident upon the objective lens; a first focus error generating means for generating a first focus error signal indicating an error between a condensed spot position of the first laser beam and the recording layer based on an output signal of the first photodetecting means; a second focus error generating means for generating a second focus error signal indicating an error between a condensed spot position of the second laser beam and the guide layer based on an output signal of the second photodetecting means; a first focus control means for controlling the objective lens in an optical axis direction thereof in accordance with the first focus error signal; and a second focus control means for controlling a magnitude of the diffusion or convergence of the second laser beam by the magnification conversion element in accordance with the second focus error signal.