The invention provides an optical disk device, which carries out a stable operation of a reflection-type photo sensor that detects a position of an optical pickup unit and to simplify an assembly process. The optical disk device includes: a chassis (11), an optical pickup unit (13) which is disposed in the chassis (11) and is moved in a radial direction of the mounted optical disk so as to carry out at least one of recording and reproducing of a signal on the information recording surface of the optical disk, a reflection-type photo sensor (15) which is disposed in the chassis (11) and includes a light-emitting unit (25) and a light-receiving unit (26), a reflection unit (21) which is disposed in the optical pickup unit (13) and reflects light emitted from the light-emitting unit (25) according to movement of the optical pickup unit (13) so as to be incident on the light-receiving unit (26), and a black member (16) which is disposed at a position facing the reflection-type photo sensor(15) of the chassis (11), wherein the chassis (11) is provided with a mold portion which is formed by mold forming, and wherein the black member (16) is integrally formed with the mold portion.