To provide a lighting optical device capable of forming a bracelet-form lighting pupil distribution in a peripherally-polarized state while restraining light quantity loss well.

This lighting optical device includes a light flux conversion element (50) for forming a bracelet-form light intensity distribution on a predetermined surface based on an incident light flux. The light flux conversion element is constituted of: a first basic element (50A) formed of an optically-rotating optical material, for forming a first arcuate region distribution based on an incident light flux out of the bracelet-form light intensity distribution; a second basic element (50B) for forming a second arcuate region distribution; a third basic element (50C) for forming a third arcuate region distribution; and a fourth basic element (50D) for forming a fourth arcuate region distribution. The respective basic elements have mutually different thicknesses along the light transmitting direction.

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