A fiber unit has an illumination fiber and detection fibers. The illumination fiber and the detection fiber comprise a soft portion that is bendable, a distal end hard portion provided at an end thereof and having a greater hardness than the soft portion, and a pitch conversion portion that connects the soft portion and the distal end hard portion and changes a distance between adjacent fibers at the distal end hard portion with respect to a distance between the adjacent fibers at the soft portion, by bending and extending. 1.0 degree
