To suppress variation of a distribution of radiated light depending on a position of a radiating unit in an information acquisition apparatus that uses an articulated arm as a waveguide unit. A waveguide unit (103) includes a plurality of first waveguides (103c), (103g), and (103k) that guide light in a direction parallel to a radiating direction in which the light is radiated from a radiating unit (105) to an object (123), at least one of second waveguides (103a), (103e), and (103i) that guides the light in an in-plane direction perpendicular to the radiating direction, and a plurality of articulations that each include therein a mirror disposed so as to substantially perpendicularly bend a wave guiding direction. The light is guided through the plurality of first waveguides (103c), (103g), and (103k) in the same wave guiding direction.
