In an optical pickup, an optical guide member is provided in an optical path of light from a light source, and has a plurality of inclined surfaces inclined with respect to a light beam emitted from the light source. A light-receiving element is provided for receiving light and for converting the received light into an electrical signal. The optical guide member and the light-receiving element are contained in a packaging member. The light beam from the light source is reflected by the plurality of inclined surfaces of the optical guide member, and then are directed to a recording medium. The reflected light from the recording medium is directed to the light-receiving element. At least one of dry air and inert gas such as nitrogen gas is charged in the interior of the packaging member at a pressure of 0.5 atm to 1.5 atm, thereby preventing the optical characteristics from being degraded.