An optical pickup device includes a light unit for irradiating a light beam having a wavelength longer than 650 nm onto a recording medium and receiving and detecting a light beam reflected by the recording medium, and an objective tens formed of a single lens having an NA of 0.7 or more to form a light spot on the recording medium by condensing an incident light beam emitted from the light unit. A recording medium has a recording density of a DVD family or more and is formed of a material suitable for a long wavelength of 700 nm or more so that a reproduction signal by a reflectance of a recording surface is optimized. Thus, a compact high density optical recording/reproducing apparatus which is inexpensive and has high performance can be realized.