An optical pickup free from tracking error signal variation when playing back a double-layered disc, and coping with incompatible optical discs, such as BDs and HD DVDs, includes a laser light source, a first polarization rotation element for rotating a polarization direction of an optical beam from the source, an optical branching element disposed in a position after the polarization rotation element to reflect or transmit an optical beam according to polarization of the beam, first and second object lenses for focusing the reflected and transmitted optical beams onto first and second optical discs, respectively, a photodetector for sensing reflected light from the first and second optical discs, and a second polarization rotation element disposed after reflection or transmission of the reflected light from the first and second optical discs conducted by the branching element, to rotate a polarization direction of the reflected light.