A light blocking device includes a deformable member deformable in a first direction and elongating in a second direction intersecting with the first direction, a plurality of light blocking plates arrayed along the second direction, each of the plurality of light blocking plates being connected to the deformable member, so that adjoining blocking plates of the plurality of light blocking plates partly overlap with each other, and a plurality of actuators arrayed along the second direction and which cause deformation of the deformable member. At least one of the plurality of light blocking plates is tiltable independently from the other light blocking plates in response to deformation of the deformable member. A light blocking region is thereby defined, based on edges of the plurality of light blocking plates.