A communication hole (55) is provided in a pickup base (51). A laser light source (61) is provided at an end of the communication hole (55). A grating (71) is provided at another end of the communication hole (55). The communication hole (55) is provided with a heat radiation path (81) which connects the inside of the communication hole (55) with the outside of the pickup base (51). Heat generated from the laser light source (61) is radiated from the heat radiation path (81).