In this coupling device (1) the position of an end section (31t) on the retracted position side of an outer case section (31) when a camera holding member (7) is being used does not protrude to the retracted position side relative to the position of an end section (41t) on the retracted position side of an inner case section (41). As a result a coupling device can be provided that comprises a structure whereby a vial can be held by a holding means regardless of the size of the vial.
