An optical part linkage device in which a threaded portion and positioning protrusions are formed at the outer periphery of a lens barrel that holds a lens. A threaded portion that can be screwed to the threaded portion of the lens barrel is provided at the inner wall surface of the holder to which a CCD package is mounted, with a plurality of positioning recesses being formed at an end of the threaded portion of the holder. After rotating a grip portion of the lens barrel in order to link the lens barrel to the holder by the threaded portions, the grip portion is turned bit by bit in order to position the protrusions with respect to the recesses by shifting them one at a time. When the rotation of the grip portion is stopped in correspondence with an optimal focal location, the protrusions engage the recesses of the holder. In this state, the protrusions do not separate from the recesses of the holder unless a strong force is applied thereto, so that the state of engagement is maintained. The invention provides a low-cost optical part linkage device that allows the positional relationship of two optical parts to be easily and precisely fixed using a simple structure.