Abstract: An optical element comprising a transparent body 10 including a first end face 12; a second end face 14 forming a prescribed angle to the first end face; and a third end face 15 having a plurality of light reflection parts 16a-16d formed on, which respectively reflect a plurality of light signals entering one of the first end face and the second end face to cause to exit at the other of the first end face and the second end face, a pitch of the plurality of light reflecting parts formed on the third end face, which are projected on the first end face being a first pitch, and a pitch of the plurality of light reflecting parts formed on the third end face, which are projected on the second end face being a second pitch which is different from the first pitch. The light emitting element array, etc. including the light emitting elements, etc.