a 2 × 2 optical fiber switch has a structure that does not produce an alignment error between the position of the central axis of optical fiber assemblies with lenses and the symmetry center position of rectangular prisms , thereby obviating the need of the skill for assembling adjustment . the 2 × 2 optical fiber switch is provided with first , second , third , and fourth optical fiber assemblies with lenses that are disposed such that the optical axes thereof are parallel in the same reference plane . the optical fiber assemblies with lenses are supported by a lens holding member . a prism holding member is supported by the lens holding member such that it supports first and second prisms and moves between a coupling position and a retreated position in a direction perpendicular to the reference plane .