An optical pickup including a light source unit having a first radiating unit for radiating a light beam of a first wavelength, a second radiating unit for radiating a light beam of a second wavelength and a third radiating unit for radiating a light beam of a third wavelenght, a collimator lens having different focal lengths dependent on the first to third wavelengths, and an objective lens for condensing light beams, radiated from the first to third radiating units, on an information recording surface of an optical disc, and a recording and/or reproducing apparatus employing the optical pickup, are disclosed. The optical pickup and the recording and/or reproducing apparatus are used for recording and/or reproducing the information for plural sorts of the information recording medium of different formats. Certain components of the optical pickup are used in common for the different light beams to reduce the size of the device as well as to correct the spherical aberration.