An optical pickup includes a radiating plate made to abut against a rear surface of a laser diode by positioning an engaging hole provided penetratingly in a central portion of the radiating plate concentrically with the laser diode. Slits are formed in the radiating plate to form a pair of tongues in the manner of point symmetry about an axis of the engaging hole. Screw insertion portions formed in the respective tongues are communicates with the slits. As screws are passed through the screw inserting portions and are screwed in, the radiating plate is secured to the base. When the screws are screwed in, the axis is positioned on a phantom line connecting points of application of force generated at proximal end portions of the tongues. Distances from the axis to the respective points of application of force are set to be substantially identical.