To provide a light adjustment device that can suppress an increase in size of an entire device even if a movable area of a diaphragm blade increases.

The light adjustment device comprises: a first substrate and a second substrate that have an optical aperture respectively formed; at least one light adjustment means; a spacer that is disposed between the first substrate and the second substrate and defines space in which the light adjustment means is operable; and drive means that drives the light adjustment means disposed on the first substrate. By the light adjustment means being driven by the drive means, the light adjustment device is configured to alternately rotate the light adjustment means at a first stationary position retreating from the optical aperture and at a second stationary position superposing the optical aperture, and adjust incident light passing through the optical aperture. The light adjustment means is protrudable outwardly from the first substrate and the second substrate when the light adjustment means stays at the first stationary position.