A light optical device capable of forming a bracelet-form lighting pupil distribution in a peripherally-polarized state with a light quantity loss satisfactorily controlled, the device comprising a light flux conversion element (50) for forming a bracelet-form light intensity distribution on a specified surface based on an incident light flux. The light flux conversion element comprises a first basic element (50A) formed of an optically-rotating material, for forming a first arcuate area distribution based on an incident light flux out of bracelet-form light intensity distribution, a second basic element (50B) for forming a second arcuate area distribution, a third basic element (50C) for forming a third arcuate area distribution, and fourth basic element (50D) for forming a fourth arcuate area distribution. Responsive basic elements have mutually different thickness along the light transmitting direction.