Small-sized and light-weighted optical pickup apparatus capable of eliminating the effect due to the flaring light rays and performing the signal detection of high reliability is provided.In the apparatus, the quarter-wave (.lamda./4) plate and the reflection-type birefringent prime provided with the deflecting function of deflecting the reflection light rays reflected on the optical information recording medium and the light rays flux separating function of separating the reflected light rays from the outgoing light rays are disposed in the optical path between the semiconductor laser constructing the optical pickup portion and the objective lens, and the light-receiving element for receiving the reflection light rays from the optical information recording medium which are defleced and separated by the reflection-type birefringent prism is disposed on a single (same) substrate together with the semiconductor laser.