Provided is a rotary optical fiber unit which can achieve a high coupling efficiency at a low cost and can easily be recovered even when a coupling unit has failed. Provided is also an optical coherence tomographic image forming apparatus using the rotary optical fiber units. A first optical fiber FB1 to transmit a low-coherence light to a second optical fiber FB2 in an optical rotary joint 6 and a cladding of a second optical fiber FB2 are inserted into a capillary 151 so as to couple to each other. The second optical fiber FB2 and a third optical fiber FB3 are detachably attached via a connector unit
