To provide an optical control element which suppresses reflected light generated by an interface between a carbon nanotube and a body having a different refractive index from the carbon nanotube, and to provide an optical control unit using the optical control element.

The optical control element characteristically comprises: an optical fiber having an end surface obliquely cut in a direction tilted from a surface perpendicular to a propagation direction of light; and the carbon nanotube which is fitted to the obliquely cut end surface of the optical fiber and used as a saturable absorber.