An optical pickup for performing data recording and reproduction with respect to both CDs and DVDs and a disk apparatus incorporating the optical pickup. The optical pickup comprises a CD laser diode and a DVD laser diode, and creates a composite CD/DVD laser beam using a composite prism. An optical film is formed on a composite plane of the composite prism to reduce concentration of the DVD laser beam in its central portion relative to that in its peripheral portion to thereby obtain characteristics of concentration distribution which is flatter than that of Gaussian distribution. For a composite prism of a type which transmits a CD laser beam and reflects a DVD laser beam, the optical film is adjusted such that a reflection rate of a DVD laser beam is minimized for a DVD laser beam incoming at an optical axis incident angle.